I've had the Huawei mobile broadband for almost a month now, and honestly, speeds were perfect. Typical speeds reached 30-50 mbps, which is unbelievable and I didn't expect that high of speeds! Sometimes during the day it would drop down to about 20, but that's okay because of the traffic etc...
The past week however, have been really disappointing. I thought it was just the timing or maybe just a bad day, but for the past week now I'm getting speeds of less than 1mbps, and sometimes can't even do a speed test, and this is 99% of the time. Now, sometimes it will go back to normal for about 10 minutes or so, but then go extremely slow again. My phone's 4G speed (also with 3) hasn't changed and is still fast, but it only seems to be the MBB speed that's changed.
I don't have broadband from 3 but I have seen others talk about this exact problem here. Try sending them a message to see what they did. The advice I can offer is. Turn it off and on, stick it to an upstairs window, change it to 3G. Other posts included that stuff And Google
I am not a Three employee. I'm just a little helper