Speed Issues with XR80 in PassThough

AirLink Routers
1

Hi,

We recently acquired 5 XR80 units with the 5-in-1 dome antenna. These XR80s do not have integrated Wi-Fi. We are using T-Mobile IoT SIM cards through Control Center with unlimited data and no speed restrictions (ambulance service). I confirmed this morning with TMO that there’s nothing that can affect or block full 5G speeds. I also tried the same Sim Cards in other modems (Sierra MP70 and Cradlepoint R980 5G and got full speed)

We are deploying one unit in a mobile command trailer and one in a remote office inside a building.

On the trailer, the antenna is roof-mounted and properly secured, same installation method we have used many times on other vehicles. In the office, the antenna is mounted on top of the rack facing a window. A Cradlepoint R980 was previously installed at that exact location and consistently delivered 300+ Mbit/s without issues.

Both XR80s were initially running firmware 4.x.x.x. At boot, they connected to T-Mobile but showed a warning indicating no APN was defined, so they used the GENERIC carrier profile. The cellular LED flashed green (4G) for a short period, then switched to purple (5G).

We configured IPv4 passthrough via Network → WAN Services → menu → enable IPv4 Passthrough and assigned it to Ethernet Port 1 (5G). Each XR80 is connected to a UniFi Ubiquiti Gateway Max. This same setup worked flawlessly with Cradlepoint R980 5G modems.

With the old firmware and the GENERIC carrier profile:

  • Office unit: ~320 Mbit/s down, 55 Mbit/s up

  • Trailer unit: ~165 Mbit/s down, 34 Mbit/s up
    (Both tested at the same location.)

After upgrading both units to firmware 5.3.66, the XR80s automatically detected T-Mobile and selected the APN fast.t-mobile.com. Speed tests with this APN were extremely poor, around 25 Mbit/s down and 2 Mbit/s up.

We then manually configured the APN to static.iot.t-mobile.com, which is the APN recommended by T-Mobile and used on all our other IoT devices. Performance improved to approximately:

  • 110 to 125 Mbit/s down

  • 35 to 42 Mbit/s up

However, this is still significantly below the performance we observed with the old firmware using the GENERIC cellular profile.

Has anyone seen similar behavior with XR80 firmware 5.x?
Could this be related to passthrough mode, carrier profile changes, APN handling, or something else?

Thanks in advance for any insight.

2

Hi @ITMedic,

Welcome to our community!
To narrow down the issue, could you please answer the questions below:

  1. Based on the description, I understand that the speed with FW 4.x.x.x and the GENERIC carrier should be higher than that with FW 5.3.66 and the TMO carrier. Please try switching from the TMO carrier to the GENERIC carrier on FW 5.3.66 and check if the speed improves.
  2. Please try inserting a different SIM card into your XR80 and check if the speed improves.
  3. Please try inserting your T-Mobile SIM into another device and check if the speed improves.
  4. Could you please generate/send the troubleshooting package for XR80?
    On the modem UI, go to System → Logs → Troubleshooting Package
    image
    image1051×195 25.7 KB

    Once the package is generated, the “DOWNLOAD PACKAGE” button will become available. After the download please save the *.tgz file and share it with me.

Thanks,

3

Hi! After replacing the unit with another one, the speeds are now fine. I think it may have been a temporary issue with the local tower at that time.

Last week, the XR80 trailer was at an event site and kept losing its internet connection. This happened regardless of the location. The issue was observed at three different locations where the trailer was parked for over 8 hours each time, as well as after returning to the office.

I would like to share the logs with you but when I tried to upload it, it told me the new users cannot upload attachments.

These devices are still under warranty and subscription plan until 08/2026. I also opened a ticket though the Support Portal/Chatbot with Semtech support and still don’t even receive a reply about that …

4

Hi @ITMedic,

Based on your description, I understand that after replacing the unit, the speeds are now fine.
You are currently experiencing an issue with losing internet connection on XR80. Regarding this issue, please create a new post so that I can better support you.

Thanks,