Is the Arris MVG468MQ router compatible with Verizon issued LTE Network Extender for better cell signal?

I was upgraded to Frontier fiber optics on July 14.2022. I previously had Frontier DSL/Broadband Max.

I was issued a Network Extender through Verizon to boost my cell signal. It worked great with my DSL.

Now...now it hasn't worked since I got Frontier fiber optics and a brand new Arris MVG468MQ router. 

My Network Extender 'thinks' that it is working...it looks as if it is working...but people cannot hear a 

word I say anymore when I call them. No ones phone will work in my house...they can call, but no one can hear them either.  My phone works fine everywhere but in or outside my house. It isn't my phone.Verizon says it's Frontier's problem.  Frontier says it isn't them...it's Verizon. 

It's been over a month of not being able to make calls from my house and have anyone hear me. 

I really need my phone to work.  I've tried adjusting some configurations in my router...to no avail. 

Nothing I've read to try, works.  My Net Extender still looks like it is working...but there is NO OUTGOING

AUDIO.  Incoming audio is as it should be. 

Somebody must know something...Frontier doesn't get it, Verizon doesn't get it...they don't listen, they have no solutions, they blame each other. 

Help??  Thank you.