I recently got the 3gbps plan. Was issued with Nokia XS-204X-A ONR and installed 2 days ago.
Followed the guide found in the forum to set to bridge for LAN1 (10G) port and connected my OPNsense router. So far, very stable, didn't notice any issues. My OPNsense router only has 2.5G, and speedtest showing about 2.1Gbps speed, which is normal.
For setting the LAN port as bridge, I also login to superadmin using "support" as username, and the password is the reverse of what was printed on the label at the bottom of the ONR.
Selected "Create a new Connection" in the Network->WAN page, Connection mode set as "Bridge mode", "Enable/Disable" is ticked.
I also set the VLAN according to what was shown for the original WAN connection, which is in my case: "Enable VLAN" is ticked and the "IP mode" set to "Add svlan", with "VLAN ID" as 10, didn't change the "VLAN PRI" which is default 0. And just tick the LAN port to bind, which in my case is LAN 1, only. My OPNsense router did not need to set any VLAN on the WAN side, just normal DHCP client on WAN side.
YMMV, I do not have any other services connected to the ONR, such as TV box or phone line. Not sure if this settings will affect those or not.
Bridge at your own risk.
Just wanted to update the forum, since I am very grateful to achieve this bridging setup with Singtel's ONR due to reading these forums.