Randomly occuring DHCP and/or DNS issues

Hello there,

I am facing a weird DNS/DHCP-issue to which I just can't figure out a cause or a solution. I am using OpenWrt 18.06 with close-to standard configurations on a GL.iNet GL-AR750. The problem I have is occuring in the local network, at random times the internal DNS resolution just seems to stop working and the router is no longer accessible through its hostname (IP works fine). At the same time, wireless clients trying to authenticate with the router fail during the process with the error message "could not obtain IP adress". When looking into the wireless settings, I can see the "Host" section only showing IP adresses, no hostnames anymore. This occurs at completely random times, sometimes a reboot fixes the issue, sometimes not. I have tried factory resetting OpenWrt several times, but no luck.
Help is very much appreciated, thanks in advance.fsd

Perhaps you can remove dnsmasq and install odhcpd and unbound and see what happens.

as I said, I did a factory reset several times but the problem kept occuring.

Are you issuing additional DNS servers to LAN clients via DHCP, or only using the router's DNS server?