Thanks for reaction,
procedure is as follows
open the web browser with url from PI (in my case 192.168.2.101)
max2play gui opens
select Settings/Reboot tab
try to do a list from plugins (but I get same error if I try to launch one of all the help functions on the right side)
a new tab opens in the webbrowser where I read the message Oeps…etc and in that message is mentioned the SSL error. So no yellow text or Debug window. I get the feeling that I am doing something very stupid?