After installing LMDE 2 on two different laptops, I had the same problem on both: The wireless, which had previously worked flawlessly, began failing, and the only solution I found that worked was to reboot the machine each time it happened. Unacceptable.
On one of the machines, I tried upgrading the OS. After rebooting, Cinnamon failed to start. I reinstalled again, and immediately upgraded and rebooted. Again, Cinnamon failed to start after the reboot. The fallback GUI that did come up is complete crap. Boo!
I decided to try the MATE (Gnome 2) desktop instead, following this how-to: How to install MATE in Linux Mint Cinnamon Edition. I followed the section Install MATE using Software Manager (the software manager is available in the fallback GUI). Note that the name of the package is mint-meta-debian-mate on LMDE 2.
After rebooting, you need to click on the Ci icon in the top right corner of the password dialog. Choose MATE from the pop up menu, then log in. Fix the ridiculous default where minimised windows disappear by right clicking on the task bar, choosing + Add to Panel …, then selecting Window List and clicking Add.
The upgrade seems to have fixed the problem with the wireless driver. I discovered from the Linux Mint forums that the problem with Cinnamon is known, and has been there since April 2016. The workaround is to apt-get install cinnamon. Why this seemingly simple to fix problem has not been addressed is a mystery. Sorry, Mate, but I like Cinnamon better.