I use a GL-X750 for internet access while I travel, and recently wanted to try out verizon to see if they have better coverage, and I wanted to do it without a major commitment of funds, so I went and got a Visible SIM. Issue is - it seems that the GL-X750 does not recognize this SIM, or know the APN.
This is quite a simple fix, log into your device and you want to click “Manual Setup” for the Modem.
You then want to select /dev/ttyUSB3 and enter the appropriate APN.
VSBLINTERNET for me.
Once you are done, apply, and you should connect and be good to go.
This worked for me, your milage may vary. Visible is designed for mobile phones, not hotspots/routers.