I am using a RPI 3 B+ with a Touchscreen. It worked for almost a year but since 2 weeks the pi is no longer connecting to wifi. The adapter is there, I can even select my wifi, enter my password but then nothing happens.
Using a wifi dongle, I was able to connect to my wifi without issues.
I swtiched out the pi and the issue is the same.
The pi is usually powered by the Touchscreen controller-board. So I tried powering the pi from an external source. That did the trick, wifi is working as normal.
While testing I noticed that there is a short low voltage warning while booting (yellow lightning bolt).
The touchscreen's power supply must be causing an issue while booting, rendering the on-board wifi adapter useless.
Would it be possible to delay the initialisation of the wifi adapter to some time after the boot when there is no high load on the power supply?
How can I troubleshoot the issue further and find out why the adapter is not connecting?
Why are wifi dongles working and the on-board wifi isn't?