In an attempt to reproduce similar test result variations directly in the speedtest.net App, I used an App called NoRoot Firewall. On Android, it acts as a virtual VPN allowing you to control what apps can access the Internet and what port numbers they can use. To start with, I ran the Speedtest App with the firewall App enabled and did a test with my workplace Wi-Fi as I know Eir does not perform any noticeable traffic shaping. The left test result is with only ports 80 (http), 443 (https) and 8080 enabled and the right test result is with only ports 80 and 443 enabled.
As shown above, Ookla’s Speedtest has no problem working with port 8080 blocked, at least with the download test. The upload test result on the right is actually higher than the VDSL modem uplink speed, which is synced at 8Mbps.
Now let’s repeat this test over the Vodafone 4G network which produced a much higher test result with port 8080 on the previous page. In this area, the Vodafone network usually peaks about 32Mbps. Port 8080 is open on the left test result and blocked on the right test result:
So while the Speedtest App had no problem running its test over a common HTTP port number, due to port 8080 being blocked, it’s pretty clear it could not deliver the same high test result figures without the special treatment port 8080 seems to get on the Vodafone network. In fact, the download test result with port 8080 blocked was close to the TestMy result over regular HTTP on the previous page.
Let’s head to the next page where we take a look at how to test your own ISP…