Blynk Local Server - Portredirection by Sophos UTm

Blynk Servers Local Blynk Server
1

Hey guys,

I have setup an own blynk Server that was running without a letsencrypt certificat.
Now I have a Sophos UTM home license and redirected all incoming traffic on my dyndns from port 443 to 9443 to my server.
I can connect with a valid certificat to the webpage but not inside the app. What am I doing wrong?
Is here anybody that got it working behind port redirection?

In the blynk app I setup port 443 and not 9443.

2

Or an other question:

Is there anything else, that the app is doing when connecting to the local server?
Or just trying to reach to host with the set up port inside the app?