When I'm using my laptops built-in mobile broadband modem, skype cannot connect.
Additional symptom: After signing out of skype, I cannot sign in again. (Sign in works fine on wifi)
Everything else (internet connection from browser, dropbox, etc.) connects without problems.
- Ubuntu 14.04
- Thinkpad T440
- Modem: Sierra Wireless EM7345 4G LTE
When using wifi, skype connects fine.
When using the same sim-card, inserted into a mobile wifi box like huawei E5776, skype can also connect without problems. (This is via wifi to the huawei box, and via gsm from there).
a) that it is not my ISP blocking anything. (also, according to their technical support they are not blocking).
b) that the problem is related to the use of the modem connection from ubuntu. It could be a problem with the modem (firmware?), or with ubuntu/modemmanager/networkmanager.
I suspect this has something to do with ubuntu and/or skype treating the wireless broadband connection differently from a wifi connection. Perhaps it has something to do with dialout, with 'metered connection', etc.
I checked the permissions on the modem device, only root had access to the device. The device did not have the dialout group, as described in this bug: https://bugs.launchpad.net/ubuntu/+source/udev/+bug/1032865
I added the device to the dialout group as described in the bug. After the fix:
crw-rw---- 1 root dialout 180, 0 Aug 26 11:09 cdc-wdm0
I also added my own user (the user running skype) to the dialout group, as described here: Changing permissions on serial port
BUT this did not solve the problem.