First rule of home automation also applies to routers: the model number matters. Different people have different experiences with different models.
If you would like to see what other community members have done to provide uninterrupted operations when the Internet goes out, go to the quick browse lists in the community – created wiki, look down near the bottom of the page for the “project reports” section, and then choose the “power“ list. There are a number of different ways to approach this requirement, and several project reports have been posted. 
https://thingsthataresmart.wiki/index.php?title=How_to_Quick_Browse_the_Community-Created_SmartApps_Forum_Section
Back to you that “the model number matters“ rule. The specific Netgear device you linked to has some limitations
- Works with any GSM Carier, including ATT and T-Mobile. Device will not work with Verizon or Sprint.
( actually, it will work with Verizon in some areas, but only with a hotspot account.)
And depending on the terms of your account, you may have to have a specific “hotspot“ contract rather than just using your regular phone.
vIt’ll work with a T-Mobile SIM meant for a hotspot, which has a 22gb per month cap. It will not work with a SIM that is meant for a cell phone on an unlimited data plan.
And again depending on your specific account, you are going to have to pay $10-$20 a month to keep the hotspot data available for this device. At $240 a year plus tax that may be more than many people want to pay.