I have pihole running on my NAS, and my DHCP server is configured to return the NAS IP as the primary DNS server (and 1.1.1.1 as the secondary). From ChromeOS settings I can see the expected DNS servers are being used, and I can reach the NAS using the local DNS records configured in pihole. Earlier this morning I was in a Crostini linux terminal and I could SSH to my NAS by hostname, then all of a sudden it stopped working in the terminal. I can still use the local DNS names in ChromeOS and other devices just fine. Inside the terminal I can see the usual 100.115.92.93 in /etc/resolv.conf, and when I run nslookup nas.lan it's able to resolve the lookup.