I have the AX88U and am using Merlin/CakeQoS. I tend to play CoD Warzone with friends and I've experienced a lot of lag (constant orange/red squares at the side of the screen to indicate a connection issue). I'm not sure if this problem is:
- Cake QoS
- Virgin Media
- Battlenet / CoD servers
My friends in the same servers don't have any issues (Xbox), so I guess that discounts the CoD servers from being the problem - although they're maybe not as sensitive to lag as I am, because they're not that great at the game.
Virgin Media don't prioritise any traffic on their network, so that could be an issue.
CakeQoS - the big unknown.
I was playing on Sunday and Monday evenings and had a perfect connection. My in game results were way above what I normally achieve and it was noticeable that when I shot, they died.