Some commands to debug DNS issues.
Manually setting the DNS in Windows will help narrow down issues. You may also need to mess with browser specific DNS settings now that DNS over HTTPS is a thing.
This command will output the requests to dnsmasq.
dnsmasq -qk --log-queries --log-facility=-
On Linux, you can use dig to look at DNS information:
dig test.example.com @dns.ip.address
On Windows, you can use nslookup instead of dig:
nslookup test.example.com
Flush the DNS, this will need to be in administrator mode:
ipconfig /flushdns