Partially Solved -
I disabled DNSSEC on the PiHole and this resolved the DNS issues on my laptop. So though I am up and working, I will now see how I can get DNSSEC working for the laptop.
In short, how do I flush the DNS cache or reset DNS?
Out of the box Librem 14, PureOS 10.0 - The system crashed when I plugged in a USB-C dock. Upon reboot I did not have network connection (it was working before) due to DNS not resolving IP addresses.
After some troubleshooting I ran
sudo chattr +i /etc/resolv.conf and was able to get DNS working again. Except websites I tried while the network was down are not now resolving. For example, when I run dig duckduckgo.com I get a blank A record. Dig @220.127.116.11 duckduckgo.com returns 18.104.22.168
If I manually change the WiFi DNS server to 22.214.171.124 my DNS server sees the request from the laptop to 126.96.36.199, but locally dig returns a blank A record for DuckDuckGo.
resolv.conf is pointing to my DNS servers (one local pihole, two external). No other systems on my network are having this issue.
Somewhere in the system the DNS is stuck.
I have tried rebooting, sudo killall -HUP dnsmasq, forgetting the WiFi network and reconnecting.
Is this something to do with dnsmasq, avahi-daemon, etc?
Any ideas welcome,