Internet connection issues with NextDNS

Since I set up NextDNS as private DNS in Android, I have issues with connection sometimes. It's usually when I restart my phone. Then I have exclamation mark that there's no internet. Webpages also do not load (no error, just constantly loading). The fix is to re-enable WiFi or switch to cellular. Then it USUALLY works for some time. Sometimes pages randomly don't load too.

I think the issue was from the beginning when I firstly used your DNS. I had to wait almost a minute to load a page, even your configuration page. At that time I didn't use specific blocking lists, so I don't think it's an issue.

I used before 2 other private DNS providers and while there were delay issues sometimes, I've never was forced to restart connection

Is there anything I can do to fix this issue? I don't want to use unencrypted DNS IPs. Thank you!

The confusing part is that when it works, it works really fast. But if the issue appears, it affects whole internet connection. :(

PS: Checked again a few times by restarting phone. Same issue with general "dns.nextdns.io". On the other hand Adgu... DNS works correctly.