Hi Lars,
No worries, I understand you are trying.
On Chromecast, I set my region to Singapore.
On Almond+ 2.4GHz:
Wifi region is set to Singapore
Wifi mode: 11NGHT20
Wifi Channel: 9 (2.452GHz)
On Almond+ 5GHz:
Wifi region is set to Singapore
Wifi mode: 11ACVHT40
Wifi Channel: 149 (5.475GHz)
If you don't mind, would you try reseting your Chromecast and connect to an Almond+ with the above settings?
If not, I wouldn't mind trying your settings if you can provide them.