I just found out a bug:
Create a New Channel (doesnt matter if you register the channel or not) with the "Default" Flag->Switch to this Channel->Delete the original "Default" Channel->Disconnect from server->You can't connect to the Server anymore. The Web- and Telnetserver stay online
tested a bit more, and found a workarround:
edit the original "Default"-Chan, and remove its Registered Flag. Do NOT switch to this channel. disconnect from server and reconnect. now the original default chan isn't available anymore