Q I recently bought a MacBook Air, primarily for travelling. When staying in a UK hotel with free Wi-Fi, on trying to connect, I saw an error reporting that “another device on the network is using your computer’s IP address (192.168.199.200)”. Which is at fault: their router, or my computer, and how can I prevent this from happening again?

A Unless otherwise advised, when using WiFi services like this, you should let DHCP assign your MacBook Air its IP address: in Configure IPv4, set it to ‘via DHCP’ (note when in countries that require IPv6 you should follow local guidance).

Provided that is how you had configured your Network pane, then the error rests with their system and not yours. If you encounter this again, open the Network pane and check.

If the error persists, then it is most probably a problem in the DHCP server of the WiFi network. You can try reporting it, but usually the hotel staff do not know what to do, and are unable to help. You could then try getting a free meal or other hospitality in compensation, perhaps.

If you a reliant on establishing an Internet connection when you are on the road, consider ‘tethering’ through your iPhone, or a MiFi hub which will connect wherever you can get a decent 3G mobile phone signal, so that you need not depend on ‘free’ WiFi services.

Updated from the original, which was first published in MacUser volume 27 issue 17, 2011.