On the local network, devices receive network settings via the DHCP server located on the ER8411 gateway.

At some point, the DNS service on the ER8411 gateway stops working properly. Computers can't resolve network printers and network scanners can't scan to PC via SMB.

During this times DNS queries for regular internet resources are resolved correctly trough ER8411, but queries for hosts on the local network receive the response "Non-existent domain." This issue applies to both network printers and Windows devices.

So, I see the printer name KM25C37F and its IP address in the Omada DHCP reservation. However, when I try to nslookup km25c37f , I got the error "UnKnown unable to find km25c37f: Non-existent domain."  Meanwhile query for google.com returns full set of google IP addresses.

Looks like DNS registraion of DHCP clients got broken sometimes. 

How can I fix it?