So in my house we have been on Fibre for a while. Since about a month or so ago I have been getting NAT types issues with people on PS4 (Cannot talk or play with friends). I have tried every method suggested to fix this e.g. opening ports, setting static IP etc. I recently did a speedtest and my PS4 gives me an error on IP Fragmentation and that my router may not support it. I have tried changing the MTU and other suggestions I have seen did not work either. Any help would be great, if its an issue router do I have to pay for a new one or will one be sent for free? (Had a lot of issues with the line before and was forced to pay even when the problem wasn't fixed)
Edit:
I forgot to mention I never used to get this problem and started getting it with multiple friends all at the same time. Don't know if it matters but I also noticed on Speedtest it also shows I'm on Tiscali now, this changed from TalkTalk around the time it stopped working I believe.