[Bug]: DNS resolving with IPv6

[someuser307]

Summary

Dear Defguard Team,

we have observed an issue on some clients regarding ipv6 and DNS.
When connected to vpn, we couldn't reach some web-servers over https, even though we could resolve the hostname with nslookup. But ping and tnc could not resolve the hostname.
This fixed the problem on the clients:
Disable-NetAdapterBinding -Name "*" -ComponentID ms_tcpip6
After that, resolving hostname with ping, tnc and with the browser succeeds and we get access to the web-servers.

But since this is not applicable for some apps, we need a central solution for Defguard.
It could be helpful, if there was an option to disable IPv6 for the defguard-client/network adapter from the server.
Is that possible?

Best regards

Steps to reproduce

1. Having an internal web-server, which uses a public domain
2. Hostname resolving not working for ping/tnc or web browser
3. nslookup working correctly

Expected behavior

-dns resolving over vpn using IPv4 only
-ping and tnc resolving hostnames
-web access possible

Actual behavior

ping, tnc and webbrowser not resolving/reaching the server

Defguard version

1.6.6 and earlier

Environment details

Windows

Deployment / install method

Docker / Docker Compose

Relevant logs / output

Relevant configuration (redacted)

dns servers and search domains are added and split tunneling activated. routes to dns servers exist and dns working fine.

[t-aleksander]

Hello, do the domains you couldn't reach have an IPv6 address assigned (for example alongside an IPv4 address)?

[someuser307]

Hello, no the don't have anything to do with IPv6. No IPv6 Address on the servers side, no ipv6 DNS entry.