T-Mobile US not connecting

General
1

I am trying to run a T-Mobile US home Internet SIM card, but my Pi5 is not connecting. Is there a trick that I am missing?
Background, I was a beta user of the service. T-Mobile wants me to upgrade my plan to get a new modem, I don’t want to.

2

Hi,

Are you connecting using PiFi Kit (USB) or just the Pi itself?

And are connecting via the port on Pi to a LAN port on your T-Mobile router?

One quick thing to also check is PiFi App > Settings > Network Settings and ensure Port is set to WAN if connecting via cable to router

3

I am connected to my mesh router via Ethernet, but I do not have this bridged to my T-Mobile router. The app says WAN.

4

Few questions so I can understand your setup:

  1. Is your mesh router broadcasting an AP (wireless network) that is online - i.e you can see a network from this mesh router in WiFi Settings and it provides internet access?

  2. When you connect to your mesh router via ethernet - is that to a LAN or WAN port. LAN would mean Mesh gives PiFi internet access, WAN would mean PiFi becomes the primary router.

  3. Can you give me model numbers for both mesh router and T-Mobile - I’ll make a quick picture for you

  4. Are you also using PiFi Kit USB Adapter or just the Raspberry Pi itself?

If you answer all four questions, I can help you get up and running. If you only answer some, it’s harder for me to do so.

5
  1. My mesh router is broadcasting an AP
  2. My mesh router is connected via WAN
  3. Mesh - Deco X20
    T-Mobile modem - Nokia 5G21
  4. Pi5 by itself

My desired setup would be to eliminate the T-Mobile gateway modem. My Pi5 would become the 5g modem using a WaveShare HAT and Quectel RM520G M.2 5g adapter. The Deco mesh would remain my AP after connecting to the Pi5 via Ethernet.

6

Ok, so for now:

  • T-Mobile Modem (LAN) → PiFi (WAN, which is the default for the port)

  • Then a cable would connected (LAN - PiFi) to WAN in Deko - this would need a USB-to-Ethernet adapter (as a second port is needed)

**
Of course, if you manage to get a HAT/M2 board then it could replace the T-Mobile part - if it’s still going to use an ethernet (therefore there’s internet-in (WAN) and internet-out to Deco (LAN) you’d still need the USB-to-ethernet adapter)

Unfortunately, I have no familiarity with those boards (or the RM520G) or any potential driver configuration that may be needed. I think for the specifics of setting up the HAT I’d check OpenWrt forums / reddit to see if someone else has configured it like that - bearing in mind PiFi is based on OpenWrt and fairly close to stock.

It’s an interesting setup - if you get further ahead with it, I’d be keen to hear what you find.