Kiwi Syslog Forwarding

Hello everyone. 

I have a vpn connection between my cloud platform and on-prem server. On the cloud I have a vm with kiwisyslog installed(free version for testing purpose) and on-prem we have another vm behind a NAT which has kiwi syslog installed. The aim is to forward the logs from on-prem vm to my cloud vm.

While checking the data-in in my vpn, I can see there is some data flow through my s2s tunnel, same thing on premise, I have data flow out. the problem is that on the cloud vm, I am not receiving any sort of syslog messages in my kiwi syslog. I made sure that all the port required are open and listening. On premise kiwisyslog we have the forward to host that point to my cloud vm. 

Please can anyone help me to clarify where is the issue? and please if you require more details let me know, I am still new to kiwisyslog.

Thank you so much