Success! Finally Verizon SS3 & firmware update works!

I owned a Motorola Arris Surfboard SBG6782-AC wireless DOCSIS 3.0 modem and was never able to connect to SS3 with the app or browsers with a Verizon SS3 base station.  We are on Xfinity. App never worked 100%. Browser worked 10% of the time. Months of troubleshooting with SimplySafe techs and supervisors did not improve the situation (although they really tried).  Thanks to @samspano4 post (see below), I wondered if Arris was not compatible with SS3
https://simplisafe.com/forum/customer-support-forum/installing-and-using-simplisafe/connecting-to-wifi#comment-3231126

I purchased these Netgear devices to replace my Arris and now everything works perfectly:
Netgear CM1000 - Ultra-High Speed Cable Modem--DOCSIS® 3.1
Netgear RBK22 -- Orbi AC2200 Tri-band WiFi System
Note: Router Firmware Version - V2.2.1.210

Setup was incredibly easy. I followed all Netgear defaults except I changed my wireless name. Network is broadcasted. Netgear automatically assigned 2.4ghz to SimpleSafe, all other devices were automatically assigned 5ghz. I did not have to modify allow/disallow in the devices for each band.  I have multiple special characters in all passwords. Dynamic DNS used, no assigned IP's were assigned on any device. I did not make any special configurations in the router. Remote access disabled (by default).

After installing the new system, the update came through about 3 hours later.  I tried to update from the keypad and it initially failed (out of range).  I moved the keypad right next to the SS3 base (I read that on this forum somewhere) and everything installed perfectly.

For the first time since we've had the Verizon base, SS3 keypad Diagnostics, wifi settings are now shown. Phone App works as expected - counts down and works well remotely (near and away from wireless signal). Any browser (on Mac, Windows or Android) for Simplisafe Dashboard now works 100%. Yeeeee haaaawwww!!!

I have never seen the "WiFi" and "Cell" in the keypad diagnostics before (see below), although the keypad always showed it was connected to my base station (on the Arris).  Here are my new SS3 Verizon keypad diagnostic settings:

Keypad
Serial:  (shows my serial #)
Version 1.2.16
Loader:  0.9.0
Hardware: 1

Base:
Version 1.2.16
Loader:  0.9.0
WiFi:  1.2.2
Audio:  1.2.2

WiFi:  (shows my wifi)
Internet:  Reachable
IP:  (shows the IP)
MAC:  (shows the MAC address)
Channel 02
RSSI:  -32db

Cell:
Status:  Ready
RSSI: -85db
Carrier:  Verizon
Network:  (shows the our network)
IP:  (shows our IP address)


So it appears, SS3 Verizon may have a compatibility issue with Arris Modems. At any rate, moving to Netgear helped @samspano4 and myself.   Hope this helps everyone!