I had this problem as well. Wound up solving it by buying some powerline adapters. Would have been a huge upgrade; went from 30-80 ping on average to 10-30, even with many people on the wifi. Only problem is I bought the cheapest ones available, like $15 for a set from TP-Link, and they like to disconnect at random. Sometimes it's once a week, sometimes 3 times a day, and I have to un and re-plug the adapter to get them to reconnect. Luckily the whole process only takes about 2 seconds for me, but if your power outlet is out of arm's reach then definitely do not go for the cheap option. also if you do not like the .0001% chance of you losing connection for a second during a fight
anyway point of the story is powerline adapter work good