I recently moved house and while I wait for my Telstra cable connection to be sorted (address issues) I got myself an Optus home wireless broadband modem which is 4G based. For $80 per month I get 200gb of data at capped speeds of 12/1mb.
One problem I encountered however was Netflix wouldn’t work for me, literally wouldn’t load. I soon came to realise that basically a lot of sites were slow to load. But oddly enough OzSpeedTest, Speedtest.net and Optus’ own speedtest were all reporting 13mb speeds.
Were the speedtests all lying? Was traffic fast initially and then dying off? I was determined to fix this.
After some debugging and snooping of the traffic, I isolated it to https only traffic. After some Gooling, I came across something that has existed in Windows since Vista called autotuning.
What this seems to do is change how the traffic is sent and received. To make my 4G connection sing again, all I had to do was open a command prompt window with admin permissions and type:
netsh interface tcp set global autotuning=disabled
After that, browsing my lightning fast, Netflix started working and all was well again. I was ready to really give it to Optus, but this saved them a berating. Upon further reading, this seems to be a problem affecting only Optus for some reason, Telstra and Vodafone are not affected by this.