Netgear Nighthawk M5 MR5200 WAN issue

I to have had persistent and ongoing wan outages (reported to Netgear mid December), but I don't use IP passthrough.

The outages are random (sometimes 3-4 days between drop-outs, and sometimes multiple dropouts in a single day, but usually up for 2 days before a reboot is needed).

Sometimes both the web interface and the M5's wifi are inaccessible (usually requiring two reboots before the system recovers completely), but usually a single reboot through the web interface is adequate to restore the WAN link when the internet is down. Sometimes the internet is down, despite the router reporting that it has a 4G connection (per Netgear advice, I've locked the router to 4G, and set ethernet standby to disabled).

I don't believe that a carrier idle time-out is the cause of my problems, as I have had outages occur during conference calls and VPN sessions during the day, and where I have configured a device to send ping traffic every 5 minutes (to be fair, most outages _do_ occur overnight, but I've long given up creating artificial traffic to see if this helps). 

I don't have the option to move to a data only SIM (contract lock-in.... 4G is my only home internet option), but definitely going to explore the factory reset option discussed earlier in this thread. Still amazed that there is no syslog logging facility to assist with troubleshooting.

Finally, I would say that my M1 router was way more reliable than the M5, and may yet be put back into production. Not sure what I would do with the M5 (I couldn't in good conscience resell something I knew to be unreliable, and I can't return the unit).

[edit:typos, clarity]