I did a bunch of things, like install a VPN and a system monitor and also clicked on 'Software Update' which downloaded and installed about 250MB of updates. Now it is running Armbian 22.08.4 Focal.
Not sure if installing the 250 MB was the best idea. A shitload of things could be installed now that interfere with the miner.
You also didn't mention what settings (mode, fan settings) you are running the miner with.
Thanks for your help, mxnsch!
I had set the miner to all three setting to try it out, left the fan on auto. But it did not seem to make any difference, the fan was not running any faster on turbo vs eco or balanced. But it was never properly connected to a mining pool, so I ignored that.
Anyway, I have downloaded and flashed the apollo-btc-mcu2_250722.img.xz onto a different 16GB SD card and started the Apollo with that new SD card. It was again working as it should, i.e. red light starts flashing and the ASICs make heat even when not connected to a network. Did not complete the initial setup steps this time, password still futurebit123, but tried to connect to WiFi and set up a VPN before connecting the miner to a pool.
But then I got no internet connectivity, although WiFi was connected.
So therefore I shut down my WiFi, Apollo and laptop to start fresh.
The Apollo decided not to start at all, just make a lot of fan noise. Twice. Then it started and ended crashing due to unknown error, rebooting. Now it's running and mining (for jstefanop.apollodefault), using 80W for 1.29 Th/s in ECO mode.
But I still cannot connect to the internet.
Seems like Apllo is so intent on mining and downloading the Bitcoin blockchain that it's next to impossible to set it up with a VPN before it leaks your IP address and announces to the world that you try to mine Bitcoin.
I might be wrong, this is not my area of expertise, but I'm not impressed so far.
I got to stop typing, I'm spitting chips after a wasted night of little sleep trying to make this Apollo work.