There is a recurrent and very much difficult to solve instability of the wifi connection on the 2008 MacBook Air due to the chipset, causing various trouble on Ubuntu ranging from
- connection to Wifi but no connectivity
- keyboard and mouse lacking
- irq conflicts
What happened is that each time the connection seems to work again, but after some time there is a connection, but no internet, and the compatibility issue is such that the previous found solutions don't work anymore!
I'll propose here a workaround supplying a stable solution to the problem.