asuswrt and google chromecast - permanent connections building up to port 8008

Hi -

I have a google audio chromecast connected to an Asus running Asuswrt, after a few hours I get a number of connections built up between random ports on the asus and port 8008 on the chromecast.

Not managed to wireshark for long enough to catch the initial connection, so have no idea if this is being initiated by the chromecast or asus - suspect the asus as the port always stays the same on the chromecast. If I run lsof, the random ports are all owned by the networkmap process.