I have a Synology RT1900ac router with DNS server. It has only one local master forward zone. Really simple one with a few entries, I just followed this guide. It was working fine until the latest router firmware and DNS Server package update. After a few hours the DNS server stops responding to queries. I need to restart the router and DNS responds again, but only working for a while. Restarting the package or reinstalling doesn't help, only restart does.
This issue is quite similar to this one: link.
I've opened a ticket at Synology, waiting them to reply. Do you have any idea how can I debug or how to fix it?