Trying to log on to Skype earlier in the week on my MacBook Pro didn’t work. For some reason it simply wouldn’t connect – it just timed out. Everything else worked absolutely fine, no issues.
Figuring it was an IPv6 issue, I unbound IPv6 from en0 and tried again. Nothing. It wasn’t my Cisco ASA firewall playing games either, although logging on to it showed a vast number of packets dropped from 192.168.1.x on its inside interface (reverse path check, I don’t use 192.168.1.x internally). How could this be?
It turns out that I had a 192.168.1.x bound to en0 from when I was testing out some locally connected kit. Skype saw this as the first IP address it could use and bound to it – whereas everything else worked fine letting the OS choose. Unbinding this address made Skype leap in to action.