When Client.Net is not specified, the client should be able to switch to TCP when UDP is not available · Issue #14 · ameshkov/dnscrypt · GitHub

See the details here:
https://github.com/AdguardTeam/AdGuardHome/issues/3947#issuecomment-996530792

> cause: read udp 192.168.11.183:61037->149.112.112.10:8443: read: connection refused