New Ubiquiti setup! Still a work in progress.

[stanlawj]

Hmm, no issues with my UCG-Fiber and 2x U7 Pro XG. Could it be either hardware issues, or perhaps its the UTP cable? Is the cable brand new, or reused (from the AC AP) ? Since the AC AP would connect at 1Gbps, while the U7 Pro XG would connect at 2.5Gbps on your POE port so require better quality.

Mine one connects to the 2.5Gbps POE port, another connects at 10Gbps to the 10G SFP+ adapter (with Unifi 10G POE injector) ..both are ok with no issues and new CAT6 structured cabling.

I leave everything in AUTO mode, don't need to hardcode to 2.5Gbps or 10Gbps

Thanks, I suspect cable issue due to POE voltage drop over long cable or interference with my other AP. Or just need to do factory reset before start over from scratch configuring, given that all the latest firmware updates were released recently.

 

[stanlawj]

Changed port link speed to 1G FDX and U7 Pro XG connection issues disappeared.
Cable swap did not solve the issue.
This means there is an issue either within UCG Fiber (software or POE+ port) or U7 Pro XG (software or 10G port).*

https://community.ui.com/questions/...o-2-5GbE/af53b148-b666-4239-a2e0-6a2ec989a1f2

Not to beat a dead horse, but I'm also having the same problem with my U7 Pro XGS (Firmware Version 8.4.6 / Network 10.0.162). Like everyone else, manually negotiating at 1 Gbps FDX completely resolves the issue. I can also confirm that manually configuring the switchport to 2.5 Gbps FDX (as opposed to auto-negotiate) doesn't help. I originally had this connected to my USW-24-PoE and it worked well considering all ports are 1 GbE. I then recently purchased a USW-Flex-2.5G 8 PoE and proceeded to spend two full evenings racking my brain trying to figure out what the issue was. Pretty damn irritating. I'm glad to know there's a workaround of some sort, but this is certainly not acceptable.

Definitely seems like a firmware/driver issue with the 10GbE port.

I wonder if it also struggles with a 10GbE link. I assume it works perfectly fine with 10Gbps and 1Gbps but has issues with 2.5Gbps and 5Gbps.

Sucks for me because I've spent a lot of money to build out a 2.5g network.

-----
1G FDX is still enough for me, just that it sux to know 2.5G compatibility issue existed. I still need to buy the 10G POE++ injector and pair it with the 10G RJ45 port on UCG-Fiber.

*This looks similar to Realtek's issues with 2.5Gbe.

1. Realtek NIC Driver Limitations

Realtek’s Windows 11 drivers struggle with full-size Ethernet frames (MTU 1500), especially during high-throughput uploads.​

​

Symptoms include TCP retransmissions, QUIC anomalies, and malformed packets observed in Wireshark.​

​

These issues are exacerbated by offloading features like Large Send Offload and Checksum Offload, which misreport packet boundaries or delay ACKs (I already had these disabled).​

2. Windows 11 Network Stack Regression

Windows 11 introduced changes to congestion control, flow scheduling, and offload handling that affect Realtek NICs disproportionately.​

​

Uploads stall or throttle when NICs fail to negotiate clean MTU boundaries or misalign TCP segments.​

​

VPNs like NordLynx bypass this by enforcing a tunnel MTU (e.g. 1420), avoiding fragmentation and offload conflicts.​

3. MTU Mismatch and Fragmentation

Desktop NIC was using MTU 1500 by default, but couldn’t reliably transmit full-size packets.​

​

Router and wireless clients handled 1500 MTU perfectly, confirming the issue was not router-induced.​

​

Manual reduction to MTU 1400 resolved fragmentation and retransmission, restoring full upload speed.​

 

[SNAG]

Changed port link speed to 1G FDX and U7 Pro XG connection issues disappeared.
Cable swap did not solve the issue.
This means there is an issue either within UCG Fiber (software or POE+ port) or U7 Pro XG (software or 10G port).*

https://community.ui.com/questions/...o-2-5GbE/af53b148-b666-4239-a2e0-6a2ec989a1f2

Not to beat a dead horse, but I'm also having the same problem with my U7 Pro XGS (Firmware Version 8.4.6 / Network 10.0.162). Like everyone else, manually negotiating at 1 Gbps FDX completely resolves the issue. I can also confirm that manually configuring the switchport to 2.5 Gbps FDX (as opposed to auto-negotiate) doesn't help. I originally had this connected to my USW-24-PoE and it worked well considering all ports are 1 GbE. I then recently purchased a USW-Flex-2.5G 8 PoE and proceeded to spend two full evenings racking my brain trying to figure out what the issue was. Pretty damn irritating. I'm glad to know there's a workaround of some sort, but this is certainly not acceptable.

Definitely seems like a firmware/driver issue with the 10GbE port.

I wonder if it also struggles with a 10GbE link. I assume it works perfectly fine with 10Gbps and 1Gbps but has issues with 2.5Gbps and 5Gbps.

Sucks for me because I've spent a lot of money to build out a 2.5g network.

-----
1G FDX is still enough for me, just that it sux to know 2.5G compatibility issue existed. I still need to buy the 10G POE++ injector and pair it with the 10G RJ45 port on UCG-Fiber.

*This looks similar to Realtek's issues with 2.5Gbe.

1. Realtek NIC Driver Limitations

Realtek’s Windows 11 drivers struggle with full-size Ethernet frames (MTU 1500), especially during high-throughput uploads.​

​

Symptoms include TCP retransmissions, QUIC anomalies, and malformed packets observed in Wireshark.​

​

These issues are exacerbated by offloading features like Large Send Offload and Checksum Offload, which misreport packet boundaries or delay ACKs (I already had these disabled).​

2. Windows 11 Network Stack Regression

Windows 11 introduced changes to congestion control, flow scheduling, and offload handling that affect Realtek NICs disproportionately.​

​

Uploads stall or throttle when NICs fail to negotiate clean MTU boundaries or misalign TCP segments.​

​

VPNs like NordLynx bypass this by enforcing a tunnel MTU (e.g. 1420), avoiding fragmentation and offload conflicts.​

3. MTU Mismatch and Fragmentation

Desktop NIC was using MTU 1500 by default, but couldn’t reliably transmit full-size packets.​

​

Router and wireless clients handled 1500 MTU perfectly, confirming the issue was not router-induced.​

​

Manual reduction to MTU 1400 resolved fragmentation and retransmission, restoring full upload speed.​

Had my own fair share of 10gbe issues with the UCG-Fiber. Some troubleshooting steps. I don't know what is your topology, assume you're connecting via the 10gbe SFP port, via POE injector.

Try the following, in this order. And if you don't face any issues, move on to the next option. This will help to isolate the problem.

1) Short cable run. Direct connection to AP, via the 2.5gbe POE port
2) Short cable run. POE injector via 10gbe WAN port (not SFP)
3) Long cable run. POE injector via 10gbe WAN port (not SFP)
3) Long cable run. POE injector via 10gbe SFP port

 

[stanlawj]

Had my own fair share of 10gbe issues with the UCG-Fiber. Some troubleshooting steps. I don't know what is your topology, assume you're connecting via the 10gbe SFP port, via POE injector.

Try the following, in this order. And if you don't face any issues, move on to the next option. This will help to isolate the problem.

1) Short cable run. Direct connection to AP, via the 2.5gbe POE port
2) Short cable run. POE injector via 10gbe WAN port (not SFP)
3) Long cable run. POE injector via 10gbe WAN port (not SFP)
3) Long cable run. POE injector via 10gbe SFP port

1) Short cable run. Direct connection to AP, via the 2.5gbe POE port
2) Short cable run. POE injector via 10gbe WAN port (not SFP)
3) Long cable run. POE injector via 10gbe WAN port (not SFP)
4) Long cable run. POE injector via 10gbe SFP port

Number 1 was one that failed at 2.5G and only pass at 1G full-duplex.
Number 2 and 3 worked for you? My theory is that this is the right config that should be working.
No. 4 will consume the last dedicated path for external 10G switch, so this isn't optimal.

 

[TanKianW]

Just some sharing.

• Supplying power (POE) through copper cable usually requires better-made cables. Sometimes the physical connection may work, but it does not mean it carries the power reliably​
• On the field, I had my fair share of issues with some "branded" or structured (embedded) cables, POE switches and injectors. Nothing beats a reliable Fluke tester (not for everyone) for verifying and troubleshooting port and cable issues. If not for most home users, only blind testing​
• When it comes to PSU to the POE appliance/injector, I will also prefer "over spec" it or choose a more reliable power source​
• Most HW/SW support for 2.5G has always been flaky (esp under load); I will always skip it and go straight to 1G/10G​
• Personally, I also don't prefer "Auto" settings, especially when it comes to POE. Some switches even come with auto-detect, which I normally disable and manually specify the voltage range. Sometimes direct power source is much more reliable than POE​

 

[1 Ghz]

Just some sharing.

• Supplying power (POE) through copper cable usually requires better-made cables. Sometimes the physical connection may work, but it does not mean it carries the power reliably​

Just replaced analog CCTV in the home with PoE CCTV from HikVision.

The contractor used solid copper cables for the new Cat6 wiring, also from HikVision. And he declined to install wall panels for the connection to the NVR, due to PoE reliability concerns. So the cables are exiting the trunking with male RJ45 connectors.

So far, no issues with PoE over the new wiring.

 

[stanlawj]

Just some sharing.

• Most HW/SW support for 2.5G has always been flaky (esp under load); I will always skip it and go straight to 1G/10G​

This flakiness is always due to cheap Realtek chips. Market always use cheap chips for cheap products, so Realtek is the dominant chip used for networking.

 

[stanlawj]

Just replaced analog CCTV in the home with PoE CCTV from HikVision.

IP CCTV cameras only need 100 Mbps speed.

 

[stanlawj]

TIP: UCG-Fiber's Network controller application doesn't enable DFS channels in the WIFI AP by default. Enable the "Extended 5 GHz Spectrum (DFS)" to unlock the extra channels to avoid interference from neighbour's WIFI.

 

[stanlawj]

so far so good. Happy to report rock-solid stability for current UCG-Fiber on stock plain settings with no VLANs and no IDS, with U7 Pro XG on POE+ capped at 1G connection speed.
Iphone's automatic roaming between U7 Pro XG and the older AP AC HD also works very well.

 

[kashix]

so far so good. Happy to report rock-solid stability for current UCG-Fiber on stock plain settings with no VLANs and no IDS, with U7 Pro XG on POE+ capped at 1G connection speed.
Iphone's automatic roaming between U7 Pro XG and the older AP AC HD also works very well.

Why your U7 Pro XG only 1G? The PoE adapter bottleneck?

 

[stanlawj]

Why your U7 Pro XG only 1G? The PoE adapter bottleneck?

2.5G intermittent connection issues. UCG Fiber does not have 10G RJ45 with POE.

I'll be shifting over to 10G when the I get the POE+ injector.

 

[sacredrays]

2.5G intermittent connection issues. UCG Fiber does not have 10G RJ45 with POE.

I'll be shifting over to 10G when the I get the POE+ injector.

only ucg-fiber affected?

i'm using udr7 with poe+ injector for my u7pro xg like no issue for 2.5gbe over cat5e cable

 

[stanlawj]

only ucg-fiber affected?

i'm using udr7 with poe+ injector for my u7pro xg like no issue for 2.5gbe over cat5e cable

Apparently, I do have issues with the combination of UCG-Fiber and U7 Pro XG at 2.5G. I don't know why.

 

[kashix]

Apparently, I do have issues with the combination of UCG-Fiber and U7 Pro XG at 2.5G. I don't know why.

I’m using the same setup, no problem. The U7 PRO XG is connected to UCG-Fiber 2.5G PoE.

 

[ykeen]

Changed port link speed to 1G FDX and U7 Pro XG connection issues disappeared.
Cable swap did not solve the issue.

1) Short cable run. Direct connection to AP, via the 2.5gbe POE port

Apparently, I do have issues with the combination of UCG-Fiber and U7 Pro XG at 2.5G. I don't know why.

Actually recommended to stay at OSI layer 1 (physical layer) to troubleshoot before graduating to higher layers. Since you mentioned cable swap did not solve the issue, was it to a new CAT6 cable? branded/unbranded ?

There was a similar issue and resolved by getting a brand new branded CAT6A cable (Ubiquiti or reputable brands)

A few things worth ruling out:

• Cable grade: Cat6 vs Cat6A. 2.5G is significantly more demanding than 1G on the physical cable and especially with POE involved
• CCA (Copper Clad Aluminum): Very common in cheap/unbranded cables. These usually pass 1G fine but don't do well at 2.5G. Is the cable branded? Able to verify it's CCA or not?
• Crimped ends: If the cable was field-crimped (not a factory patch), even a slightly bad crimp that 1G tolerates will fail at 2.5G. (Unlikely this, but just in case you crimp your own cables)
• Any patch panel or wall keystone within the intermediate path? Since you tested direct connection, unlikely the issue here, but if there are any components here that don't support 2.5G and above, that could be the issue too

Your 10G + PoE injector plan is actually a good layer 1 test as well.

When you get the PoE+ injector and test via the UCG-Fiber's 10G port, it helps in two ways:

• It tests a completely different physical port on the UCG-Fiber, which helps isolate whether the 2.5G PoE port itself is the problem
• It separates PoE power delivery from the data link, if the issue was actually the 2.5G PoE negotiation interfering with the link, this will reveal it

So the results would tell us:

• 10G port works fine → the UCG-Fiber's 2.5G PoE port is likely the culprit
• 10G port also has issues → points more toward the U7 Pro XG's NIC or the cable

In the meantime, if you can get your hands on a proper branded CAT6A cable (Ubiquiti's own premium patch cable or reputable brands like Belden/Panduit), that gives us another data point to compare against your 10G test or before you get your hands on the POE+ injector.

 

[stanlawj]

Actually recommended to stay at OSI layer 1 (physical layer) to troubleshoot before graduating to higher layers. Since you mentioned cable swap did not solve the issue, was it to a new CAT6 cable? branded/unbranded ?

There was a similar issue and resolved by getting a brand new branded CAT6A cable (Ubiquiti or reputable brands)

A few things worth ruling out:

• Cable grade: Cat6 vs Cat6A. 2.5G is significantly more demanding than 1G on the physical cable and especially with POE involved
• CCA (Copper Clad Aluminum): Very common in cheap/unbranded cables. These usually pass 1G fine but don't do well at 2.5G. Is the cable branded? Able to verify it's CCA or not?
• Crimped ends: If the cable was field-crimped (not a factory patch), even a slightly bad crimp that 1G tolerates will fail at 2.5G. (Unlikely this, but just in case you crimp your own cables)
• Any patch panel or wall keystone within the intermediate path? Since you tested direct connection, unlikely the issue here, but if there are any components here that don't support 2.5G and above, that could be the issue too

Your 10G + PoE injector plan is actually a good layer 1 test as well.

When you get the PoE+ injector and test via the UCG-Fiber's 10G port, it helps in two ways:

• It tests a completely different physical port on the UCG-Fiber, which helps isolate whether the 2.5G PoE port itself is the problem
• It separates PoE power delivery from the data link, if the issue was actually the 2.5G PoE negotiation interfering with the link, this will reveal it

So the results would tell us:

• 10G port works fine → the UCG-Fiber's 2.5G PoE port is likely the culprit
• 10G port also has issues → points more toward the U7 Pro XG's NIC or the cable

In the meantime, if you can get your hands on a proper branded CAT6A cable (Ubiquiti's own premium patch cable or reputable brands like Belden/Panduit), that gives us another data point to compare against your 10G test or before you get your hands on the POE+ injector.

Thanks you could be right. I am testing it now with another Cat6A cable. It'll take a day to confirm stability (no drops/disconnects).

Update: Cat6A cable solved the issue. No more disconnects. Looks like I don't need the POE+ injector anyway.

 

[sacredrays]

Thanks you could be right. I am testing it now with another Cat6A cable. It'll take a day to confirm stability (no drops/disconnects).

Update: Cat6A cable solved the issue. No more disconnects. Looks like I don't need the POE+ injector anyway.

so what's wrong with your old cat6 cable? self crimped or factory?

anyway, if get poe+ injector, can use your 10gbe port although the wifi on pro xg won't hit that speed.

 

[stanlawj]

so what's wrong with your old cat6 cable? self crimped or factory?

anyway, if get poe+ injector, can use your 10gbe port although the wifi on pro xg won't hit that speed.

The Cat6A OEM short patch cable (not Ubiquiti) that I tested with is probably not Cat6A. Don't know why it failed and that led me to believe the hardware failed. I plugged and unplugged many times already, no change.

So I crimped my own Cat6A cable using 3M Cat6A (SFTP), and it passed.

 

[sacredrays]

The Cat6A OEM short patch cable (not Ubiquiti) that I tested with is probably not Cat6A. Don't know why it failed and that led me to believe the hardware failed. I plugged and unplugged many times already, no change.

So I crimped my own Cat6A cable using 3M Cat6A (SFTP), and it passed.

have you used that cable for 2.5gbps/ 10gbps connections (not poe) before? was it stable?