Verizon Router G1100 Wired Connections and 2G/5G WiFi Connectivity are not working

Hi  I got Verizon Gateway G1100 router for my Verizon 50/50 package. I have been having problems from the get go. I have exchanged 2 routers so far and I am on my third router.

Here is my setup

I have a Laptop, Cisco IP Phone, ObiHai OBi200 VoIP Telephone Adapter adaptor connected via Ethernet port.

I have several tablets, smart phone and Rokus connecting to Router via WiFi.

Here is the problem

• I can’t get any of my wired devices to connect to the router via any of the four yellow Ethernet ports on the back of the unit.
• I am not able to connect via 2G/5G wireless connections.
• I can only connect to this router using the Guest Network wirelessly.
• Hooking up my PC to the router with an Ethernet cable gets me no connection, not even to the router itself at 192.168.1.1 (or myfiosgateway.com).
• The link lights on the back light up.

Here is what I have done so far

1. I have got 2 routers so far with the same issue and they have been replaced by Verizon without any success.
2. I press and hold the reset button for 10-15 seconds to factory reset the router. Then it works for an hour or so and then I lose the connection again.
3. I have tried to have Verizon Support reset it remotely. Then it works for an hour or so and then I lose the connection again.
4. I have tried renaming the default SSID and changing the password for the 2G and 5G. It hasn't helped.
5. I have gone through other threads similar to this and their situations seem to be different. I am scared to see the results if I google "Verizon Quantum Gateway dropping connection". There are so many people who have had this issue from 2015/2015. I am surprised it continued in 2016 also.
6. I have changed channels in the 2G/5G WiFi channels and that also leads to dropped connections after sometime.
7. I have completely switched off 5G and kept only 2G and that also leads to dropped connections after sometime.

Workarounds

1. I have found the setting up the guest network works and thats the only thing I am able to use now.
2. By trial and error, I found that whenever I switch on the Cisco IP Phone then the wired ethernet connection work. As long as I have the Cisco IP Phone switched on, the wired connection works. If I switch it off, then the Wired Connection stops working. I don't usually have Cisco IP Phone switched on all the time, so I am unable to use that workaround all the time.
3. The only suggestion Verizon support provided is for me to switch to a different model (earlier model than G1100).

Things not tried yet

1. Replacing ONT Box
2. Replacing Co-Ax Jacks or Splitter