I just successfully deployed a Deco M4 system in my house and was sufficiently pleased that I bought a second set for another property I have in a different city.

For the other property, I am wondering what happens when there is a power failure since I won't be able to get to it immediately.  Typically the Internet gateway (Xfinity ISP) will come back up on its own and nearby devices will automatically reconnect when it does.  Other devices including those presently going through a TP Link range extender do not.  I am not sure whether this is a range extender issue or something else.   Hoping that the Deco will let me toss the range extender and have a much more powerful, resilient, and stable home network.

Should I expect the M4 units to reconnect automatically to the Xfinity router or should I look into uninterruptible power supplies? 

If I should get UPSs, are there any specific features I need to look for?  The APC BE425M seems like it would work:   I tried to include a link but I think that's not permitted for new posters.  I figure 1 each for the gateway+M4 base and 1 each for the satellites.