Yes, when I create the modem connection, I select /dev/cdc-wdm0 (qmi) and it works great.

Apologies, I grabbed screenshots for each of the sequence steps below, but the forum is limiting me as a “new user” to just one image upload per post.

So here is the sequence on the GL-MT300N V1:

  1. Initial connection with USB 4G modem:

  2. Swap to tethered iPhone:
    (upload://b0szSepQEfKUKJJtfCODwiTJxgG.PNG)

  3. Swap to tethered Android:
    (upload://9ZTe9k6AbIQBiYXpz494spyZcLy.jpg)

  4. Swap back to USB 4g modem:
    (upload://hDhvVRC4GJDuEslrY8TllpVJxZf.PNG)

In each case, the device regains internet without issues. The UI does not show connection for the Android, but there is internet - I setup a new interface for the android tether, which is why there is no IP in the UI.

Now, the exact same configuration on the GL-MT300N V2…

  1. Initial connection with USB 4G modem:
    (upload://Abzj6PTvGJnqr3VZTqPB8vdG2WR.PNG)

  2. Swap to tethered iPhone:
    (upload://hQrMkGCoc3tQNkDTxc6HKWWX5Tz.jpg)

  3. Swap to tethered Android:
    (upload://88jHNjJu8Eba5jaLgmd6duFsjD0.jpg)

  4. Swap back to USB 4g modem: no connection
    (upload://rViRKHEfTZe74c3xYcYGg1Hcxuc.PNG)

  5. USB 4g modem after power cycle:
    (upload://ba7qQrA4a7RPUMUViXNQlOTJzLe.PNG)

The sequence works fine (despite the blank UI) until #4 - swapping back to the USB 4g modem. No connection until #5 - power down, power up.

Any ideas why this is happening?