Troubleshooting RHEL 7.1 slow wireless speed

Question

About a week ago I installed a fresh scientific linux 7.1 image onto my laptop. The wireless worked out of the box, and worked at full speed for nearly a week up until about 36 hours ago. Then, I installed a new piece of software (Cisco Anyconnect VPN Client) tested that it worked, then shut down the computer. The next day I started it up and seemed to have slow connection speeds.

I downloaded a python wrapper for speedtest.net's tests and have been trying to do some diagnostics, but can't seem to interpret what is going on. Here are what I have measured so far:

From a different computer also running SL7.1, wired into the network the speed test gives:

Retrieving speedtest.net configuration...
Retrieving speedtest.net server list...
Testing from Time Warner Cable (---)...
Selecting best server based on latency...
Hosted by BrescoBroadBand (---) [14.56 km]: 59.823 ms
Testing download speed........................................
Download: 17.30 Mbit/s
Testing upload speed..................................................
Upload: 1.15 Mbit/s

I get similar speeds from my android phone connected to the same router through the wireless using the speedtest.net app. When I run the exact same speedtest on my laptop I get:

Retrieving speedtest.net configuration...
Retrieving speedtest.net server list...
Testing from Time Warner Cable (---)...
Selecting best server based on latency...
Hosted by Time Warner Cable (---) [17.08 km]: 216.958 ms
Testing download speed........................................
Download: 0.27 Mbit/s
Testing upload speed..................................................
Upload: 0.81 Mbit/s

which are borderline unusable speeds. I can get about 20-30 kB/s download, even when I clone a git repository from the other SL7.1 computer on the same local network. Even loading the webpage controls for the router I am connected to is very slow. If I plug the laptop into the router using a spare ethernet cord, I get full speed. Also, the above speed test was run with nethogs running in another terminal to verify that something else wasn't eating my bandwidth.

Since the change to slower speeds occurred at reboot directly after installing the cisco software, I uninstalled it, rebooted several times, and ran similar tests, but it was still slow. The cisco software is now reinstalled.

My laptop has a Broadcom BCM4313 wireless chip, which means whatever driver it is running on is not the proprietary driver provided by Broadcom (I have it downloaded but even with the suggested patches it won't build). What confuses me most is the fact that it worked fine for ~5 days.

Finally, my question is: are there other troubleshooting steps I should take, or have I seen enough to point to the wireless driver as the problem, and should I spend the significant time it will take to build it?

Answer 1

While building the proprietary driver directly did not work, I followed the instructions here for the EL7.1 distribution, and successfully build the rpm and installed it. I then followed the instructions from here to deactivate the old drivers and activate the new one with the commands

sudo modprobe -r ssb wl brcmfmac brcmsmac bcma
sudo modprobe wl

Then after a reboot, my laptop automatically connected to my wifi and rerunning the speed tests gave:

Testing download speed........................................
Download: 12.42 Mbit/s
Testing upload speed..................................................
Upload: 1.12 Mbit/s

which now agrees to with the other computers on my network.