RT-AX86U - strange disconnection problem to game server

[demonseed76]

Hello, I have a small problem that has me pulling my hair out trying to trace, originally I suspected the ISP but after some testing it has come down to my Asus RT-AX86U. The problem is, when playing a certain game, I will get randomly disconnected from the online game., like a time-out that causes me to crash and log out of it (secondlife) usually anywhere from 10 to 60 mins of low activity it will do this.

It's not the computer or Ethernet cables as it does this on two separate machines, I tested the game on another broadband connection (neighbour's EE broadband ) , and it's 100% stable I can stay logged in for hours, and overnight with no disconnect.

So I took my Virgin Media super hub 4 out of modem mode and used that as the router, and again it's 100% stable, so I now know it's not my ISP, so i thought my router was going bad, so I bought a replacement AX86U PRO., and the new router the disconnects continue to happen , when either wired or wi-fi

I have looked at the admin page, there is no traffic analysing or parental settings or anything that i can see set on. I have even tried factory resets, merlin fw, and downgrading firmware, but for some reason this router is dropping internet connections randomly or timing them out.

Any help/advice suggestions appreciated