Receive on my iPhone sounds robotic

I finally got the port forwarding to work and everything connects through SmartLink, but it sounds robotic or like it is scanning really fast. I hear conversations and they sound normal but hard to hear with the digital robotic sound all the time on every band. If I connect to SmartLink using WiFi it works fine. This sound is on iOS and macOS only when using a cellular connection. The sound is hard to explain but it sounds like a digital signal all the time through the entire band and all bands.
The setup is a little unconventional for internet to the shack. My shack is in the pole barn in a soon to be separate room. I ran a 75ft ethernet cable to the Flex 6400 from a Netgear BPL wifi router. Unfortunately I cannot put the router any closer or the BPL signal is lost or very weak. I have the transmitter for the BPL in the house about 100ft give or take. The signal is not the best but it works with speeds of 3mb down and about the same up. My internet is a wireless service meaning a dish pointing to a tower miles away. Needless to say the internet is horrible. Low latency and ok speeds when working well. My cellular is about 70mb down and 12mb up with even lower latency.
Is there a setting that I missed to fix this issue? Thanks in advance for any assistance.
73 Curt AC9HO