Screen sharing in UK between Virgin Media and BT infinity

[davebquinn]

Hi

I'm trying to share screens between two macs, both on El Capitan. I 'm pretty sure the settings are correct on both macs but when I connect to server from my machine I can't make the connection

Both machines are in the UK - My ISP is Virgin Media, my Dad's iMac is on BT infinity.

Are there issues with BT broadband - firewalls maybe?

Thanks in advance for any help

 

[Commentist]

It could well be firewalls (on either end or on the Macs), though I find the Apple screen sharing can be a bit hit and miss and tend to use ssh/terminal most of the time... I've had some success with Back to my Mac from work to home, since this seems to use some kind of tunnelling to set up the connection and works with dynamic IP addresses, but I do worry a bit about overall security when I do this (everything is then just secured by my iCloud password). If the machines share the same iCloud account, you might want to try this first before getting too deep into the network debugging?

Otherwise, the first thing to check is that the firewall on the server allows incoming connections. I would then try to ping or ssh to the server from a terminal if you know the IP address (simpler protocols than screen sharing, and will tell you if the end-to-end network is working - turn on Remote Login under Sharing). Then try setting up a VNC connection (again you'll probably need to know an IP address unless you are using some kind of dynamic DNS - X.local only works on the local area network) - use vnc://x.x.x.x as the server address from Connect to Server...

You could also try connecting from your machine on the local network to check that the screen sharing is set up and working on the server before trying remotely from your home. That will narrow the problem down to firewalls/network connection and show that the basic sharing is working OK.

 

[satcomer]

According to the Apple document TCP and UDPnports used by Apple Software you should have ports (through third party routers/firewalls) open are 16384 - 16472 open on both ends.

 

[davebquinn]

Thanks both, I'll try those