Hello Daniel France,
The logs tells me something different. How can you be so sure the phone can reach it ?
Have you done a wireshark trace at the phone end and checked ?
Did this never work or is this something new on this End of Sale and End of Support phone?
Please ensure to provide some feedback if this reply has helped you so other users can profit from your experience.
Best Regards
Steffen Baier
Polycom Global Services