TLS handshake failing

[swkillen]

I have a home OpenVPN server and Client using the unassigned port 783. The router is configured to forward the port.

When I try to connect on the guest network at work it fails via TLS handshake timeout. It seems server logs say the client isn't responding.
When I try to connect on the public wi-fi at my grocery store, it fails in the same way
When I try to connect from a restaurant/coffee shop near my office it works perfectly.

I've always used the identical device and the identical config file for all these tests.

Since it works well at one site, it seems the problem must some way be in the client interaction with the remote network. But I cannot figure it out.

Can someone help?

Thanks

-swkillen