Here is a link to a previous discussion on this topic.
https://community.verizon.com/t5/Mobile-Network-Archive/Verizon-4G-LTE-network-extender-does-NOT-work-with-fiber-optics/td-p/1256527
It has been archived and I can no longer reply. I am having EXACTLY the same issues. Switched from cable broadband to fiber (Frontier for both), and while my network extender worked fine with broadband, it does not work at all with fiber. I can make/receive calls, but nobody can hear me, nor can I hear them. I bought a newer model of the Network Extender from Verizon, and it doesn't work either (The Network Extender "2"). Toward then end of the previous discussion on this, a VZW employee finally admitted that the 4G LTE Network Extender does not work with fiber internet, only broadband (cable); this discussion was in 2022. Has anything changed since then??? Does Verizon have a newer network extender yet that works with fiber? I have no choice but to stay with the fiber - Frontier will not allow me to go back to cable, and there are no other providers in my area yet. I know Verizon has purchased Frontier in my area and will be taking over the internet service at some point in the future, but as of now my only option is Frontier and my network extender is useless. Thanks for any help on this...