Very slow connection in Pantech PX500 EVDO modem

[Antonio]

This is happening in Ubuntu Intrepid. The Pantech PX500 EVDO wireless modem is recognized immediately and the connection is established automatically. The only problem is that the connection is very very slow, in the range of the 15 KB/s in average. In the same spot but using Windows XP the speed is about 1.5 MB/s.
There is indeed a bottleneck at some point in the serial connection.

I tried to fix it changing the configuration of the connection following the manual provided by Sprint.
http://www.sprint.com/assets/downloads/linux/pdfs/Sprint_Mobile_broadband_Setup_Guide_for_Linux.pdf

With the card removed, I restarted the computer and gave the command:
sudo modprobe -r usbserial

Followed by the command:
sudo modprobe usbserial vendor=0x106c product=0x3702

The first command removed the default driver, the second is to load the specific driver for the Pantech PX500, the problem is that the card is not working at all after this process.

Restarting again the laptop, the card is automatically detected and works again but very very slow as indicated above. The rest of the hardware in the laptop woks great, the only problem is the wireless connection. This is annoying.

[Antonio (acardh)]

A Linux user had this same problem. He provided a patch for it.
http://www.evdoforums.com/thread4381.html
He was running the Pantech PX-500 too, he found that the problem is because the generic drivers (usbgeneric.ko and acm-cdc.ko) have tiny buffers designed for slow-speed modems.
I am attaching here the patch provided by him and posted in the EVDO forums.

Hope it helps.
:o)

[Alexander Sack (asac)]

i am not sure how just usbserial would work. the cdc-acm issue about buffers is known, but will not be fixed afaiu. the new thing is called cdc-ether. not sure if your modem supports that though. Anyway, nothing we will fix directlyin NM. Maybe this needs a modemmanager plugin at some point, but to file a bug there we first need modemmanager somewhere :).