Maybe its because the computer need more power, so it disconnect the LAN/WIFI connection. If you use Windows 10, there is an option on Device Manager-->Network Adapter/USB Adapter (Pick the connection you used)-->Properties-->Power Management, then uncheck -->Allow the computer to turn off this devices to save power.
This will make your connection always on even not enough power because of your GPUs.
You can see my post here.
Maybe its because the computer need more power, so it disconnect the LAN/WIFI connection. If you use Windows 10, there is an option on Device Manager-->Network Adapter/USB Adapter (Pick the connection you used)-->Properties-->Power Management, then uncheck -->Allow the computer to turn off this devices to save power.
This will make your connection always on even not enough power because of your GPUs.