Can't connect to QUIC after enabling permanent mode on OVH Firewall
Cloudflared is unable to connect to Cloudflare Network with
quic protocol, then most likely your machine/network is getting its egress UDP to port 7844 (or others) blocked or dropped.1 Reply
I don't know enough about OVH but there's probably some sort of filtering they're doing as part of this: https://help.ovhcloud.com/csm/en-gb-dedicated-servers-firewall-network?id=kb_article_view&sysparm_article=KB0043447
You should make sure you're allow listing Cloudflare IP's specifically on whatever origin firewalls you have to prevent this behaviour:
https://developers.cloudflare.com/fundamentals/setup/allow-cloudflare-ip-addresses/#allowlist-cloudflare-ip-addresses
Allow Cloudflare IP addresses · Cloudflare Fundamentals docs
Because of how Cloudflare works, all traffic to proxied DNS records passes through Cloudflare before reaching your origin server. This means that your …