Are you using pihole?
I ask because Lutris was killing my network too and it took me like two weeks to figure out the root cause. For me, this is what was happening. I had Dead Space Remake installed. Lutris used the name of the game to identify it, but was incorrect. Then it would try to download assets for the game but apparently they changed the URL path. But when Lutris failed to get them, instead of giving up, it HAMMERED my DNS with requests, triggering pihole to engage its flood controls and kick me off DNS for 5 min.
If you use pihole, watch your query log live and see what is happening.