Sounds to me like your DNS on the router itself is crashing.
There’s a couple of things you could do. Set up something like pihole or adguard home, and set the forwarding to something other than your internal DNS server.
Personally, I use AGH, and the default quad9 for forwarding all but my own domains. Those get handled by my OPNsense router’s Unbound DNS and/or DNSMasq, depending on which domain (local or one of owned domains)
Everything other than those gets forwarded to quad9’s public DoH service.
Sounds to me like your DNS on the router itself is crashing.
There’s a couple of things you could do. Set up something like pihole or adguard home, and set the forwarding to something other than your internal DNS server.
Personally, I use AGH, and the default quad9 for forwarding all but my own domains. Those get handled by my OPNsense router’s Unbound DNS and/or DNSMasq, depending on which domain (local or one of owned domains)
Everything other than those gets forwarded to quad9’s public DoH service.