I've just had this come up, I've just moved house and the same issue with the 3 three 5g router. I've done a bit of searching around and found someone online that posted the following and it's solved my problem, I've spent about two hours trying to sort it and then stumbled across this, which originally was meant to sort out someone accessing netflix, but it's now allowed my Roku to get an outside connection. Hope this helps someone in the future-
ORIGIONAL POST.
Since receiving my ZTE 5G router I have experienced many problems. The main issue being my Lounge TV wouldn’t run the Netflix app. I rang Three, then Netflix, and finally contacted Samsung, the TV is under warranty. None of the services could offer a resolution. I contacted an engineer who was unable to solve the issue. Following and during the process I searched the internet for possible causes. On finding a Forum post I discovered a possible solution.
In the router settings change the APN setting from 3internet to three.co.uk.
Netflix and all other services are now working!!!
Now, my question is: have I weakened any security issues by changing the original 3internet setting? When I log in to the router admin via the IP address 192.168.0.1 my windows 11 Edge browser address bar displays NOT SECURE!