LTE modem (router/USB) support with at least 300/150 dl/ul speed

Oops, I had the wrong datasheet in hand, but the datasheet for the 7455 says the max current draw is 1.5A (page 47 of the technical specs), although they say the maximum average current is 1A.

The specs for the ltefix.com M.2 USB enclosure here says 3.3V.

The moral of the story is that powering LTE modems via USB isn't plug and play. If you want to make sure your LTE modem doesn't periodically crash, make sure your power source can handle it.

And if you are looking to power a high performance LTE modem from USB2, you'll definitely want two USB connections.

Oh, BTW, ltefix.com is shutdown due to supply chain disruption. They were selling stuff on facebook, but they've shut that down too. The last I heard from them, they hoped to be back in business in a couple of weeks.

Short and good USB cables are also essential. Most USB data cables aren't made for 1A currents, leading to significant voltage drops. The modem brownout protection will reset the modem, looking like a crash. This can be very confusing because of the constantly varying power requirements of LTE modems. The "crashes" often appear to be related to external events, like handovers or high rate data transmission. You can spend a lot of time trying to figure out why the modem "crashes" only under some specific condition, when the solution is as simple as replacing the USB cable.

BTDT...

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Ok, so finally I've decided to build an OpenWrt based modem:

Main components:

  • RPi 4B, 2GB
  • ICY BOX case IB-RP102 Plus
  • M.2 NGFF USB 3.0 WWAN adapter
  • EM7455 M.2 WWAN module.

The T77W676 does not support the required LTE bands 1+3+7+20+28.
Does Openwrt support Intel XMM 7262/7360 e.g. Fibocom L850-GL?

Found this thread:
https://www.mail-archive.com/modemmanager-devel@lists.freedesktop.org/msg05983.html

Can sb. confirm that XMM modules work with OpenWrt?

Thank you for the information! :slight_smile:

PCIe mode is not supported. They should work in USB mode if they allow switching to that.

The Intel based modems are cheaper for a reason. Not something I'd recommend. I have bought one (XMM7160 based) myself many years ago, and won't repeat that error.

OpenWRT isn't fully baked on RPi4. I've been playing with this community build: Rpi4 < $(community_build)

Also, I recommend using a USB enclosure that has two USB connectors like the one that ltefix.com sells (unfortunately, they are shut down right now). The spec sheet for the 7455 says the maximum current draw is 1.5A which is 4.95W. USB3 supplies 5V a max 900ma. Even assuming a 100% efficient 5V -> 3.3V conversion, USB3 can only supply 4.5W.

Thank you @bmork. But EM7455 should work (in USB mode) as AndrewZ recommended this module?

Does EM7455 has any carrier/vendor limitations?
Need Telefonica/O2 compatibility. The only LTE band that is not supported is 28.
Are there any branding limitations if I use a Dell DW5811e?

Yes, ltefix.com is the only provider of that kind of USB adapter with two connectors that I could find. Found USB power Y-adapters.

Yes. My laptop has one of those, so it's pretty well tested with the Linux drivers :wink:

I'm not sure you need to worry too much about 900mA @ 5V being less than the specifed peak. The issue is more like having only USB2 (500mA) and a cable voltage drop of 1V or more. You don't necessariy need a Y cable or multiple cables.

FWIW, I am using a EM7565 in one of these adapters (the IT-NBU3A version) connected to the USB3 port of a WRT1900ACv1 using a 50cm USB3 extension cable: https://www.aliexpress.com/item/32794435102.html I haven't seen an unexpected reset yet. But this might obviously depend on my network conditions, which are pretty good.

                                         
5v                   T  2200 ()
___poly_____________/
|                   |
. . . . .         _____                        
. . . . .           -
                    -
                  _____

Thank you guys.

Hardware arrived, LTE works with the Sierra module. The T77W676 doesn't work at the moment.

How can I bridge the pi (used as LTE modem) and forward wan/public ip to my router?
Modemmanager is used as the interface.

Please use this forum category only for hardware recommendations.
For further questions regarding configuration, please open a new topic.

Thanks!

Okay thank you.

Can I use the 4G LTE adapter mentioned before for WLAN?
The Pi's chip is very slow. I'd like it to config AP mode with a Qualcomm Killer or AX200 chip.

Or are there any other wireless USB dongles that work out of the box in ac mode?

No.

Mini PCIe and m.2 slots may provide both PCIe and USB bus connections. The mentioned adapters are USB only. This works for LTE modems, because they normally use USB. WiFi modules always use PCIe.

Bmork,

I have to admit that I misspoke in my posting. I wrote WLAN and I meant WWAN. I wish to plug the aforementioned USB 4G LTE modem into one of my routers and use it for WWAN, not WLAN.

I presume from your answer that the answer this corrected question is yes?

Stuart

That's what this thread is about. There are several suggestions further up...

FWIW, most LTE modems are supported and have AT commands. Which is why you won't find a list of them.

EDIT: Except that many of the USB stick modems are configured as routers by default, which hides all the modem interfaces from the host. So it is safest to use a m.2 or miniPCIe module to be sure you have AT commands

Just my 2 cents:

Wonder if LTE CAT9 452 Mbps via USB3 is an acceptable solution (if you happen to have a router having USB3.0 port)

I am referring LTE CAT9 of LG G5 (which could be found ebay should be rather afforable)

The device you are talking about, as far as I can tell, it looks like a phone? Are you suggesting to use a phone?

I will have to look at the WRT3200ACM and determine if it has an USB3 port or not. However, a quick inspection of the Netgear WNDR3700v2 shows me it is not USB3. I presume this device would still work on USB2, just much more slowly?

Thanks

yep, it is a LG phone which was laying around featuring LTE & USB3.0
I tried & it worked for usb tethering when connected a openwrt router having either usb2.0/usb3.0 port

I bought and tested the Fibocom L860-GL and was able to switch its mode to USB. Then used MBIM but failed to actually have it working in OpenWRT. I may lack the knowledge on how to get the drivers churning or get Modemmanager to work with it.

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