Hi,
Thank you all for your patience and support for AirDroid and we are deeply sorry for any inconvenience this may have caused for all of you.
Most of the errors happen because of unstable network environment or temporary server connection failure. Usually, tying to sign in again could solve the issue.
More details of the error code:
http://help.airdroid.com/customer/porta ... code-mean-
And we are keep working on improving the stability of AirDroid Windows/Mac, you can expect a better AirDroid in the future updates
You can try web.airdroid.com, it should be working well.
Thanks again!