Network connection errors

I emailed support and got an unhelpful reply directing me to the help site even though I paid for Nextdns. I don't see why I have to do all this work and troubleshooting for a service I paid for. I have nextdns on my PC and also two android phones. On the phones it is set up via private DNS as instructed. I am also running NordVPN. With Nextdns set on the phones I have random network connection errors. As if connectivity to nextdns drops out. I have been unable to fix it. I did try using Adguard DNS instead to see what happens and everything has been fine. No random network connection errors. Using NordVPN or not. I'd like to understand why this happens with Nextdns as I've proven it is the cause since Adguard doesn't produce the same problem.