Cannot connect to remote computer from outside home network

myTeamViewer1

I am trying to connect to my Ubuntu 18.04.1 machine at home (which is connected to the internet via ethernet cable) from my Windows 10 work laptop, which is connected to the internet over guest wifi.  I have enabled easy access and can connect perfectly when both machines are on my home network.  However, when I try connecting from work it attempts the connection but never gets to the "Authentication" stage and eventually times out.  If I use my mobile hotspot however, I can connect just fine.  The guest wifi as far as I know is not public - it requires a password to connect.  Is the firewall on the guest wifi blocking it?  Or is there a setting in TeamViewer on the remote machine that can be changed to allow this type of connection?