Port 4070 blocked : Why Spotify won't connect to port 80?

[morganko]

Hey,

My office only allows Port 80 and 443 connection.

As far as I know, Spotify is suposed to try theise ports once it has detected that the port 4070 is closed.

For some reason, my client just stay offline, whereas there is no domain name restriction.

Is the Port 80 failover an urban legend? 

Regards,

[user-removed]

Hello: Just out of curiosity are you able to use the webplayer at work https://play.spotify.com/?

[morganko]

Yeah but only using the following URL, to force port 80 used : https://play.spotify.com/?http=1

[samf12345]

So I did a little digging and it appears its because at least part of the spotify app is hosted on/reliant on Google cloud servers on port 4070. These cloud servers are configured to transmit data to and from your machine using TCP, its encrypted so idk what it is. I did capture some packets though and the weird part to me is that its sending a decent amount of data (up to 1Kb packets) from your host to the google server.