Connect 360 /streaming to xbox problem since moving from Sky

[#1]

I've used Connect 360 for years with no problems.However I've just swapped ISP from Sky to Plusnet and my imac had disappeared from the list of my devices on the xbox now.I can connect fine to xbox live but Can't stream my movies at all.
I thought if xbox live was working ok then my new router must be recognised.
Any ideas people ?
Thanks in advance !

[#2]

Its possible that the Plusnet router(TG585) is on a different subnet ( 192.168.1.x ) than your old SKy router ( probably 192.168.0.x ). If the Connect360 has an IP range(or subnet) configured somewhere then you may need to change it.

[#3]

Thanks,MisterW. Not sure how to do what you suggested.

[#4]

Sadly got an an unhelpful reply from plusnet:

"Our router uses universal plug and play technology so should allow the devices to connect without any problem. This sounds like the devices have not recognised the upnp and therefore is not allowing the connection between the two devices. You can manually set up port forwarding to bypass this issue.
We do not support this feature but the router is capable of doing it.
www.portforwarding.com has a huge library of how to guides for setting up port forwards to allow devices to communicate properly on many routers including ours."
Anyone have any advice?

[#5]

Quote

Not sure how to do what you suggested.

and I'm afraid I have no experience of the mac or Connect360
Edit: you could possibly try uninstalling Connect360 ( however that's done on a mac? ) and reinstalling , maybe it self configures to the current subnet.
Or you could check any firewall settings on the mac ( does it have any ? ) I readc somewhere about Connect360 automatically configuring the mac's firewall...