Very strange that it’s just your phone on that network that’s affected. The only time I’ve experienced issues like you’re describing on a Wi-Fi network was with an iPhone XS.

I wasn’t able to fully diagnose the issue as the customer got a new phone, but we were able to make the phone play a bit nicer with a dedicated 2.4GHz only network during investigations. Can’t explain it, but hopefully someone else here can help further. I don’t think it’s something that should be resolved by a full reset on the phone as that’s a bit drastic and you’ll lose all your data if you don’t have an icloud backup.

Disable private Wi-Fi address when you’re connected to that particular network. Click the little blue i to load the network properties. It’ll constantly reconnect when the iPhone generates a new mac address. Some large wireless networks don’t handle this change very well.