Player cannot connect to photon network, error about port 27001 in log

We are using PUN+ (version 1, need to upgrade to v2 sometime) in our Unity game. One of our players is consistently unable to connect to the photon network, and this error appears in the log:

Warning: TimeoutDisconnect while connecting to: 172.65.215.189:27001. Check if the server is available.

Is there anything we can do for them?

thanks

Dave