QUIC settings
Default QUIC setting is enabled, you really no need to set anything on LSWS for it.
Firewall
To me, that nc -vu
command is not enough to verify UDP 443 port unless it will return some information back. I would recommend verify it with tcpdump, e.g.
Run tcpdump on the website's server.
tcpdump -vv udp port 443 -X
Run nc command from any client server.
nc -vu YOUR_DOMAIN 443
and you should see some output on server if there's any UDP port 443 traffic in and out.
Trust Certificate
You will need to setup HTTPS with trusted certificate. Here we can use openssl command to do a quick verify
openssl s_client -connect YOUR_DOMAIN:443
Check if the Verify return code is 0.
If above methods all shows good, please share the output result and site URL so we can check more.