Hi Akamarko,
I have the same experience: at one wifi-network it doesn’t work at all, at an other, sometimes it works, sometimes it doesn’t.
However, my notebook has Intel wifi hardware that can be configured as an access point. In that case it works well. Please note that this is not the same as an ad hoc connection.
If you can, try this.
Cheers,
MajorMinor.