Hi.
I’ve just gotten my hands on the 5B+ and I wanted to test out how well cellular modems work with it.
Some time ago I got myself a Quectel EC25 LTE modem with M.2. key B connector.
I tried it on the 3B and it was detected fine and even properly connected to the network.
However, on the 5B+ the modem does not get detected whatsoever.
Are there any additional configuration steps that must be done in order to enable the modem?
Hello Stardust,
which image are you using?
Also, are you using the emmc, sd card or nvme?
Regards.
Thanks for responding.
I tried both the official Radxa b2 KDE image, and Joshua’s Ubuntu.
By default I use an NVME SSD, but I also checked it with only an SD card.
Alright. I figured it out.
The problem was purely electrical.
When the modem is connected loosely, inclined in the slot, it makes good enough electrical contact with the pins and gets detected fine.
However, when the modem is properly screwed in, it either doesn’t make good contact or it shorts something, and therefore does not get detected.
It’s counterintuitive but it’s true.
I also noticed something that maybe could be called USB interference? When the modem is connected and screwed in, other USB ports seem to have a tiny bit of a problem working. My wireless keyboard and mouse combo stutters a lot then. Not sure if it’s my peripherals or something electrically wrong with USB, but that’s that.
Imo this issue should be looked into.
Another separate issue is the slow speeds.
I have proper antennas and APN set up, and the modem does support LTE, yet I’m only getting 8 Mbps download speed. Upload speed is good - 19 Mbps. Could someone help with that? It sounds as if the modem is forced into working in a worse mode but I don’t know why.
The port is only USB 2.0 capable so you won’t get speeds above 2.0 speeds, you’re are not close to that limit however so no idea what the problem is.
The limit will be around 280 Mbps.
Thank you. That’s not a useful response at all.
I’d say that 8 Mbps <<< 280 Mbps…
But that’s just my opinion.
It’s not listed that the m.2 b key is limited to USB 2.0 so you know something you didn’t before, sorry you don’t find it useful. I understand it’s not helpful now but when or if you get it to work correctly and it will not go faster than USB 2.0 you will know why.
As you are experiencing issues with USB and it’s a USB connected device also it is likely related, have you tried with a wired mouse and keyboard to see if anything changes? Anything out of the ordinary in the system log or dmesg output?
What power adapter are you using?
I guess. Thanks for not reacting negatively to my wording. I might’ve sounded impolite.
LTE doesn’t go any faster than 150 Mbps down and 50 Mbps up, so that still doesn’t saturate USB 2.0.
No, but later I will try and see how my board reacts.
I’m not sure. I wouldn’t really know what to look at.
A 60W USB-C PD. And I can see that PD is working properly, since I have a cable with an integrated power meter. It has an indicator for whether or not the PD protocol is working.