I have a Huawei E3276 LTE dongle (12d1:14fe -> 12d1:1506) and a problem with the upstream speed. The problem is not only present with Ubuntu 14.04 LTS (64 bit workstation, kernel 3.16), but also with Raspbian Jessie for Raspberry PI (kernel 3.14). Upstream seems to be always limited to 5 Mbit/s whenever I check the speed from the Linux computer that I use as a LTE router. The other computers in the LAN always get about 10-15 Mbit/s upstream, even though the traffic is routed through the same Linux computer suffering from seemingly capped uplink.

Downstream speed is always fine, 25 Mbit/s. I even installed Windows 7 in the same computer as Ubuntu and the speeds are 25 Mbit/s down, 15 Mbit/s up. So the problem is not with E3276 device itself or in the mobile subscription, but in the Huawei E3276 Linux compatibility. Maybe something in the kernel?

I have made sure that the matter is not with iptables rules: the speed does not noticeably increase when iptables is disabled. Turning off IPv4 forwarding does not improve speed either.

I'm not sure what settings and logs do help in debugging the situation. Please ask for more details, if you have a clue what might be wrong.

Thanks, Mytomi