Stephen,
thanks for this error analysis so far!
I added the sapjco.jar to the classpath in Agentry.ini and also copied the sapjco.jar to the Agentry folder. Now, the exception is gone and I can see in the SMP server logs, that Agentry is calling the backend and fetches the parameters from the config panel (globals and application parameters).
There is no error anymore, so I assumed it should work now. But when trying to connect from a Agentry 7.0.2 WPF Client I just get a connunication error. I checked the firewall in the system using iptables -L and it's showing that no traffic will be blocked.
Regards,
Michel