Hi @beansand, welcome to the forum 
Sorry to hear you’re having communication issues.
There are multiple possible causes for that, because there are multiple pieces of hardware involved.
- The first thing I’d check is whether you happen to have this issue, which is a known problem with some Fathom-X boards.
- If that’s not the issue I’d suggest you try bypassing the Fathom-Xs + tether setup with an ethernet cable directly between the onboard Raspberry Pi and your topside computer, to confirm whether it’s something to do with the tether setup, or one of the ends.
- If you have an FXTI box at the topside (rather than a bare Fathom-X board) then it may be worth trying to swap out the USB mini to USB A cable, and if possible the ethernet to USB converter in the box as well