Game slow down on Helix Fi - solution.

When playing Call of Duty with a new Helix Fi modem. Things would work but after about half an hour, the game would start lagging until finally it was unplayable - this is still the case as I tested this again yesterday and the problem persists. I could not find any way to set uplink QOS on the Helix Fi so finally I put it in Bridge Mode and connected my own Netgear R6400 router. This worked very well and I do not actually have to set any uplink QOS.

My question is why there is there no discussion about gaming issues with the Helix Fi modem/router here on the forum. I could not find any solution or even discussion. I've only found Redit discussions that did not offer solutions. I'm curious why this is not a bigger issue. Are other Helix users gaming - in particular COD - without issues?