Sometimes Its Not The Cellular Network When Tethering Is Slow

When I was recently in a Starbucks and wanted to get some work done over a coffee I was quite surprised that despite good cellular network coverage, the Internet connection from my smartphone to the PC via Wi-Fi tethering was behaving very strangely. Needless to say that I started to investigate…

As I wanted to download a firmware image of a couple of hundred megabits I counted on the LTE network to give me adequate speed. But all I got was half a megabit per second and very erratic round trip delay times. Moving the smartphone sometimes helped for a second or two but then data rates were done and delay was up once again. O.K. so perhaps an LTE problem I thought, let's switch to UMTS. Strangely enough I encountered exactly the same problem there!? O.k. so perhaps the phone has a problem, lets restart it. But no, again the same problem afterward!?

Now I was a bit at a loss for a moment, what else could it be? Then I realized that there is one more wireless link, i.e. the  Wi-Fi connection between the smartphone and the PC. Perhaps something strange is going on there!? So I disabled auto-channel selection in the tethering configuration and manually set a channel. And voila, LTE became lightning fast, the download of the firmware image I needed started to run at 20 Mbit/s and everything was o.k. Interesting, something must have interfered on the 2.4 GHz channel the smartphone started the tethering hotspot on. Something to remember.