Error "This router may not support IP fragmentation

Potential-Monke

Playing away on the PS4 Pro earlier today with no problems. Went away for a while and booted up the PS4 about 45 min ago. Couldn't connect to Crunchyroll so tried YouTube and same issue. Tested the speeds and getting connected but sometimes failing the PSN check.

Every time it takes 20+ seconds to get the result of the NAT, which is usually type 2 and stays that way, with maybe 1 or 2 tests out of 20 giving type 3.

Googling is saying something about changing the max MTU on the PS4, but it's always been set to auto and the PS4 hasn't had an update today. Any idea why this would start happening? Dont believe it's the router as the same happens when connected to 3 LTE, no issues that I can see on the phone on LTE or Wi-Fi. I'm perplexed!

Forgot to mention, its VF Gigabit 150 and getting 142 on Wi-Fi, 30 up. PS4 tests at under 12 down and less than 1 up.