Macs and local DNSMasq - clients keep forgetting results given by local DNS
Yes - this has been a pain for a long time and many generations of networking hardware and software.

Personally, I've given up on running my own dns and now pick one of two items.


Use mDNS and host.local for resolution and let DHCP assign addresses from a pool.
Set DHCP reservations for each device I care to connect to and use http://xip.io to resolve that IP by name.


In your case, I use 192.168.1.3.xip.io in place of server.example.com where I need to put a FQDN in for resolving a server name. I've never had this be unstable, but if you do, there are other providers like http://nip.io do the same service.