Since you are running Proxmox VE, there are two places you want to look at:
- Your containers’ DNS settings, which can be set in the WebUI when selecting your container and clicking on the DNS tab right between Network and Options. Those default to your PVE host’s settings.
- Your PVE hosts’ DNS settings, which can be set in the WebUI when selecting your PVE host and clicking on System (between Shell and Updates) and DNS.
Do not edit the /etc/resolv.conf file in your PVE/LXC container manually.
If you aren’t running a DNS server on 192.168.1.2, consider changing it cloudflare’s 1.1.1.1, Google’s 8.8.8.8 or any other public DNS resolver
You could also further debug your DNS with tools like dig, nslookup, dog, etc.