PS4 - "Router may not support IP packet fragmentation "

Router: Eircom F100

While Im getting Nat Type 2 and 15mb download this issue does seem to be affecting certain online aspects. After a short enough period in a chat (5min+) people in the chat will lag on my end and I cant hear them despite my connection speed or it will give a nat type error and it basically "mutes" that person.

Also having issues joining a friend in "Far Cry". He can join me but I cant join him. Even when he does I will lose connection to the servers after a while.

As I said its not a groundbreaking problem and I can still play online relatively fine however I do seem to experience more lag than I should for 15MB download.

Cant find much online in the way of answers to this IP packet fragmentation issue and I'm clueless. Only thing eircom related I found was suggesting it was because the MTU settings on the router didnt match what was set on the Ps4. They do for me so its that.

Just there I tried the PS4 with a lan cable to see if it was a wifi issues but still getting the error and still cant join my friend.

Any suggestions would be great.

Thanks