I’ve tried with new PSU, lightning bolt disappear but same problem.
1st : the first PSU I used is not in cause
2nd : the long cable I used drains some power but not that much
3rd : I’ve tried with an other PSU : no more lightning bolt, but same problem with the WIFI key
4th : I’ve tried with an other WIFI stick (D-Link DWA-140 to be precise) : it works.
In my opinion : there is still some issue with that realtek chipset :
USB: 0BDA:8176 Realtek Semiconductor Corp. RTL8188CUS 802.11n WLAN Adapter
That issue is not specific to osmc, but seems to realtek in linux…
I don’t have the resources (time) to help compiling the specific module for that wifi stick, but I can test and help if wanted