I'm using a Raspberry Pi 3B with a LCD-touchscreen in a project that needs an internet connection. I use the latest Raspbian release and have installed all updates. My goal was to use WiFi but as the client can't provide this I'm going for 3G. I had a Huawei E3531 lying around so it should be convenient to use that one.
I am getting it to work with usb_modeswitch, but the problem is that whenever I insert the dongle, the system starts to freeze at around 10 seconds at the time at regular intervals, like every 50 seconds or so. By freeze I mean the Pi doesn't respond to keyboard, mouse or serial input. But the cursor still blinks, and in X I can see that CPU-load is updating.
First I thought that it was because I've put the command for modeswitching in crontab to run every minute, but I've disabled that and the problem persists.
So, any ideas?