My AX90 router is dropping the internet connection every night between 1:30am and 6am.  The network is up, and all computers/devices within the LAN/WAN are discoverable, just no internet.  I get the reports every night from my Synology NAS upon disconnect and reconnect.  This is the second ISP we've had at the location, so it's definitely not the modem or the provider.  I have connected the NAS to an open modem port to test that connection for a night and it stayed connected the whole time.

Is there a setting that I'm missing like diagnostics, updates, etc. that would take the router offline for roughly 4 1/2 hours?