Network stalls unless I open Control Center on iOS

Question

This is weird, and it has been happening to me since I switched ISPs about two years ago. Sometimes when I’m doing something on an iOS device that requires a network request, like browsing the web or using an app, the request will stall. That is, it won’t complete for a very long time. Depending on the app, I might see a loading screen, a frozen progress bar, a blank screen, etc. Doesn’t matter if I’m using Safari, an app, playing a game, etc. It seems be a system wide problem.

The weird thing is that as soon as I open control center, the request completes immediately. This solution was tested on three iOS devices on the same network: an iPhone XS Max, iPhone 8 Plus, and a 6th gen iPad all on iOS 13.1. Although as mentioned previously, I’ve experienced this for about two years, so it happened before iOS 13

The issue appears to be random, but very frequent. It’s an annoyance for sure, but the Control Center trick is so reliable at fixing it that I’ve just not bothered to figure out what the problem is.

I believe that the problem has to do with my ISP’s modem (ATT) since the issue doesn’t happen when I switch from WiFi to mobile data. I have other non iOS devices on the network which experience the same random stalling, but don’t know what the equivalent of the Control Center trick is on those.

So I’m wondering if anyone has any ideas what is going on. What does opening control center do that causes network requests to complete instantly?

I’ve also tried switching DNS servers to the Google and Cloudflare ones, but that didn’t do anything