Slow WiFi/Ethernet on 2011 Macbook Pro Wifi is terribly slow (between 1Mbps and 15Mbps) on my 2011 Macbook Pro running High Sierra. On all other devices, iPad, iPhone, iMac, PC it is above 80Mbps. Ethernet is slow as well. Sometimes I hit spikes of around 50Mbps for a couple of minutes, but I don't know what triggers it.

It doesn't seem to happen if I connect to my phone's personal hotspot. Both phone and Macbook come in around 30-35Mbps, although I didn't test it for long enough to see if it's just a spike as well.

I tried everything in the last couple of days:


removing wifi network from preferred networks
renewed DHCP lease
fiddling with router settings and channels
connecting to 5Ghz and 2Ghz networks
resetting network settings by deleting network files from Library/Preferences/SystemConfiguration
SMC reset
NVRAM reset
scanning for malware
reinstalling OSX
installing El Capitan from the Time Machine backup of my iMac
turning off Bluetooth


Any other ideas that might help? Or is it faulty hardware?
Seems the problem was hardware related. Something got stuck in my ventillator which made it stop.

When the laptop overheated after 10-15 minutes it underclocked all hardware, making the internet run slow.