I have had an engineer come out a month or 2 ago for this issue I gave it some time to see if it will be fixed, I am still seeing your router may not support ip packet fragmentation on ps5 speed tests I don't seem to be lagging, but in the tests it shows very low upload speeds 10-15mb I was getting that on 250 package without the error, but since I upgraded to 1gig this is when I the "ip packet fragmentation" error message started.
Also noticed their are quite a few other with the exact same problem and no solution seems to of been found
