GL-MT3000: USB tethering on USB 3.0 disrupts 2.4 GHz repeater, USB 2.0 fixes it

Router
1

Model: GL-MT3000 / Beryl AX
Firmware:
v4.9.0

I would like to report what looks like a reproducible issue related to USB tethering and 2.4 GHz repeater mode.

My setup:

  • Repeater connected to a hotel Wi-Fi on 2.4 GHz

  • Android phone connected by USB for tethering backup

  • Multi-WAN mode: Failover

  • Repeater priority higher than Tethering

Problem:
When I connect the phone by USB and enable Android USB tethering, the repeater connection to the 2.4 GHz hotel Wi-Fi becomes unstable or drops. In my case, this could happen even before manually pressing “Connect” for tethering in the admin panel.

Important observation:
After switching the router USB mode from USB 3.0 to USB 2.0, both interfaces were able to stay up at the same time:

  • Repeater on 2.4 GHz

  • Android USB tethering

So this strongly suggests interference or interaction between USB 3.0 and 2.4 GHz on GL-MT3000 in this scenario.

Why this matters:
This makes USB tethering failover unreliable for travel/hotel use, which is one of the important use cases for Beryl AX.

Request:
Could you please investigate whether:

  1. USB 3.0 is interfering with 2.4 GHz repeater operation on MT3000

  2. The firmware could automatically warn the user when using 2.4 GHz repeater together with USB tethering on USB 3.0

  3. The router could automatically fall back to USB 2.0 mode in such cases, or provide a clearer recommendation in the UI

I can also provide logs if needed.

NAS speed problem FLint 2 with the USB 3.0
2

Hi,

Thank you for your report and suggestion.

Yes, in some cases, USB 3.0 devices can interfere with the normal operation of 2.4GHz Wi-Fi.
However, since there are other factors that can also cause interference to 2.4GHz Wi-Fi—and it’s difficult to distinguish between them—we may not be able to detect this automatically or fall back to USB 2.0.

4

Thank you for the clarification.

I understand that the interference itself may not be fully solvable in firmware and may be hard to detect automatically.

However, I think the UI/UX could still be improved a lot:

  • show a warning when 2.4 GHz repeater and USB 3.0 tethering are used together

  • add a suggestion in the USB mode settings to try USB 2.0 in this scenario

  • mention this clearly in the documentation / troubleshooting guide

This issue is not obvious at all for normal users. Without external help, I would never have guessed that USB mode could affect repeater stability on 2.4 GHz.

So even if automatic fallback is not possible, better warning and guidance would already be very helpful.

5

Thank you for your suggestion. We’ll discuss it with the product team to see if we can add a reminder to the firmware.

We actually already have a relevant documentation page, but it may be difficult to find due to mismatched keywords:

6

A warning is probably not a bad idea as this won’t just impact repeater, this would impact normal AP operation also. e.g. If someone is using as a regular router with a USB3 device connected.

7

The interference problem between a USB3 port and the 2.4 band is kind of universal with routers no matter how good the internal shielding is. Look how Asus keeps trying different locations for the port. You might try a better shielded cable or one with ferrites.

I suppose there could be an option to always switch to 2.0 when tethering is active; 5G cell speeds would need 3.0.