I experienced intermittent connection to my 3M 50 ever since I purchased it about a month and a half or so ago. It would maintain a cloud connection for a few days and then go offline until I reset it. I finally hit on a solution that seems to work. It's been online for about a week and a half now reliably and it's never ever gone that long yet.
My guess is that somehow the "mating" references the IP address and if that changes the thermostat goes offline. I tried assigning a static IP to it but that just seems to put it offline permanently, so instead I provisioned the same IP on the surfboard's DHCP server for the thermostat's MAC address and hostname. Since I did that it hasn't given me a lick of trouble. By the way the same thing works if you're using an Epson Artisan printer with CUPS on Linux. My printer at least doesn't even give you the option of setting a static IP.