Off uses Bonjour to make the connection between your iPhone and your computer.
This is the same system that iTunes uses to talk to the iTunes remote (so any troubleshooting for the iTunes remote should apply to off as well).
The Off Remote Helper app on your Mac/PC has a 'connection help' button.
Click on that for a set of tests that will let you pin down where there is a problem with your connection.
As well as giving you exact tests, the connection help will help you figure out any issues.
99% of the time, Bonjour deals with any firewall issues for you. If you are in that 1% then you may have to check your firewall settings to make sure that Bonjour and the Off-Helper are getting access.
First Check : If you are having any trouble connecting, then try turning off the firewall to test (System Preferences / Security / Firewall). If you can get the connection with your firewall off, then you can turn it on and tweak the settings to allow the required permissions.
When you install Off_Helper on your Mac, you'll be asked if you want to allow it to accept connections (say yes!)
First Check : If you are having any trouble connecting, then try turning off the firewall to test (Start / Control Panel / Windows Firewall). If you can get the connection with your firewall off, then you can turn it on and tweak the settings to allow the required permissions.
If you use the default windows firewall on Windows, then by default it will allow the connections required.
If you use another firewall (or have changed your default settings) then you need to make sure that two applications are allowed through your firewall.
depending on the firewall, you may need to reboot after making the changes
You may have another seperate firewall on your router. Again, the easiest way to test whether this is blocking the connection is to go into your router settings and turn off the firewall completely. If that works, then you can turn of your firewall again and fiddle with the settings.
NB: You can disconnect your router from the internet when playing with your firewall settings if you want to make sure that your computers are completely safe.