I'm not savvy enough to know what "bufferbloat" is

Update : finally reached out to ISP and went up in support tier. At first they said “things looked fine” on their end, but I elaborated how it seemed to ONLY have issues during gaming where the entire network would crash (router admin page was still accessible but internet across all devices was usually down for a bit right after online multiplayer gaming round of any kind would start). That seemed to get them to actually check the logs…

And so it looks like the culprit is probably faulty ONT hardware (tech said diagnostic had shown 50+ disconnects just in the past 2 days). They are coming out to replace and swap out older cat5e run from ONT to router inside the house tomorrow afternoon, so we will see if that fixes things.