copy-pasting what I HOPE is the solution in case someone with the same problem stumbles upon this:
“I was having this exact same issue on my XS Max—browsers and apps randomly stuck “thinking” until I opened the control center. I would see them immediately load in the background and close it again, and then repeat this process an annoying amount of times whenever I tried to use my home wifi. On my data I never had the issue, so I usually just stayed on there, but finally I decided it was ridiculous that I was avoiding the high speed Internet I was paying for on one of my most used devices and called Apple support.
As expected, they were as confused as I was. We went through all the basics: diagnostics, resets, checking speeds and other devices on the network, etc. but nothing helped or revealed any answers. Finally I was connected to an admin, who made some suggestions about my wifi settings. I logged into my router and ended up switching the channels of both my 2.4 and 5 GHz bands to ones with the least amount of congestion, and I also split them (that is, gave them each a unique SSID) so I could connect exclusively to the 5 GHz wifi. I didn’t do it thinking it would help my issue, I just had been meaning to make those changes for awhile to give my internet speeds a little boost.
Ever since I changed those channels and connected exclusively to the 5GHz wifi, I haven’t had any problems! I don’t wanna declare the problem solved quite yet, but it’s been hours and I haven’t had a single moment of lag. Since I made those changes at the same time I can’t say for sure which did the trick unfortunately, but I’m just happy to finally have working wifi on my phone.
TLDR: Try changing your home WiFi’s channels and/or splitting your 2.4 and 5 GHz bands. That’s assuming your problem exists on your home network; if it’s with all wifi, I have no idea, sorry!“
