iOS devices randomly receiving no internet connection while connected to M6

Does anyone experience this issue or now how to solve it? While connected to the Netgewr MR6500 I’ve noticed that intermittently certain iOS devices will have no internet connection for a few hours and nothing helps to fix it. No resetting network settings or rebooting helps. It just spontaneously stops working and then spontaneously starts working again. Sometimes it’s one regular iPad sometimes it the other iPad Pro and sometimes it’s my iPhone 12 Pro Max. PC laptops seem to stay connected better.

I’ve also added a TPlink ax1500 in access point mode to run WiFi since the m6 seemed to suffer with all the devices connected. Now I have 20 devices connected and WiFi is faster and the m6 seems to work. It’s just the random no internet connection that is killing me. The WiFi is still connected at the time. I never know which device will not cooperate that day so I end up needing multiple devices laptop ipad and iPhone to get through a work day. Super frustrating but I can’t figure out how to fix it. I also can’t keep wasting two hours a day just to get online

Any tips on fixing random “no internet connection issues?” When all the other devices are connected?