Separate power to LTE USB stick to avoid disconnects

Installing and Using OpenWrt
1

[This is a continuation of this post but discussing a new topic]

Spontaneous USB disconnects may happen after shorter or longer uptimes with various 3G/4G modems and the cause may be insufficient DC current served over USB from the router.
I have a Huawei E3276 modem connected to a WNDR3800 router and had these disconnection problems.

I have now tried putting a powered USB hub between the router and the modem but I just got the same disconnection problem again.
The hub I use is a Trust 7-port Pyramid:
https://www.trust.com/en/product/15140-pyramid-7-port-usb-2-0-hub

Should this hub normally be sufficient to rule out the DC problem when connected to wall power?

2

I'm having a similar problem with an mt76xx wireless USB card.
I don't the answer but I think any powered hub would do.

3

Btw, the power block delivered with the Trust hub is marked 5V, 2A, but I don't find any specification about how much is served by each port.

4

I think it would be a max 2A across all the ports (a max of 500mA/port).
You could assume the Trust Hub supports 4 USB2 ports if they all draw the max at the same time.
I doubt they'd all want 500mA at the same time.

The USB 1. x and 2.0 specifications provide a 5 V supply on a single wire to power connected USB devices. A unit load is defined as 100 mA in USB 2.0 , and 150 mA in USB 3.0. A device may draw a maximum of 5 unit loads (500 mA) from a port in USB 2.0 ; 6 (900 mA) in USB 3.0.

My problem is a bit different, I have both wireless and wired USB3 devices that MIGHT both need 900mA at the same time.

5

I'm using that same hub to power two HDDs and a SDR receiver, at the same time. It should be good enough to power one modem.

6

Thanks, great to know that this hub works fine for your setup!
I'll try it out some more. The logs may actually suggest that the disconnects I saw were not power-related but may be related to USB registration timing of hub versus the connected device. I need to have a further look though, at best half-guessing ATM.