Just an update, I decided to go with the 5Gbps/10Gbps game as well so that I can also carry out OOkla Speedtest and show high speed. LOL.
Singtel 5Gbps Enhanced Plan with WiFi 6 Router at $49.90/mth (U.P. $95.90/mth)
Comes with XGS-PON Optical Network Router + 1 unit of Singtel AX5400 device
Need to have two appointment now.
1) NLT -- this is pretty fast, 5 August 2024
2) Singtel -- this really takes time, the appointment will be on 28 August 2024. [Edit: improved to 12 August 2024].
There is a risk though -- if I can not get the ZTE ONR bridging working, then I am stuck with the ONR for two years. But I tend to think it is worth taking the risks with the report of the following thread -- bridging does not seem to be too difficult (but there is a report that bridging may not work now).
https://forums.hardwarezone.com.sg/threads/singtel-10gbps-zte-f8648p-superadmin-password.6946718/
Intended setup (no matter bridging is successful or not).
Bridging is ok --> good, no Double NAT
Bridging is not ok --> oops, have to go with Double NAT...