Verizon USB modems not working

I tried two different Verizon USB modems: UML290 and 551L, and I cannot make any of them work with my GL-MT300N-Mango.

I’m using a Verizon SIM card (4G LTE service) that I previously tested in GL-MiFi (with the global modem module inside), and it works fine there with full 4G speeds.

The 551L actually connects, but only gives me 3G with very low speeds. The UML290 never connects, it just keep connecting and showing “Abort” button but never completes. The router recognizes both modem as Verizon and the APN is automatically set to VZWINTERNET, which I think is the correct one. I reset both modems but no change. Is there any other trick to make these work? If not, which USB modem can you recommend that is guaranteed to work with a Verizon 4G SIM?

You can choose to set it manually and try different APN and device choices.

Sure I can do the manual setup, but I don’t know what settings I should choose. Should I try all combinations? I’m sure the APN is the right one. Other choices are below.

To close the topic, I tried my Verizon SIM card in a standard GSM modem (Huawei E397), and it works fine at 4G speeds. I suspect those older Verizon-branded modems are restricted to certain types of Verizon plans and do not support 4G speeds on new Verizon’s own 4G SIM cards.

Conclusion: if you have Verizon 4G phone service, and want to use that SIM in a modem, use a standard GSM modem, not a Verizon-branded modem.