Hello Pros!

Sorry, I'm not a computer scientist and I just hope I'm making myself understood. I use an ER7206, the OC200, several TP-Links Switches and EAPs (all with Omada) in my Smarthome. I have a Solar power system with an inverter vom Fronius (SnapIN) that can communicate via LAN (REST API). From Loxone I have a Miniserver to control my home (and my Wallbox to charge my car). I have the problem, that the connection between the Miniserver and the Fronius often stopps/is interrupted. The Miniserver says that the connection to the host fails. But at the same time the API from the Fronius is mostly reachable via Webbrowser. Sometimes it's not. I have the impression that too many fails let the whole thing crash. But without doing anything it recovers. 

The adress is http://192.168.1.80/solar_api/v1/GetPowerFlowRealtimeData.fcgi and I get some JSON.

The Miniserver has 192.168.1.30

Both are connected via LAN. Because I can reach the Fronius via Browser and because it works generally with the Miniserver I know that it's not completely wrong. But what can be the reason for this behaviour? How can it be, that via Browser it works and at the same time the Miniserver can't establish a connection? Can this be some security-/firewall issue? If yes: what could I do in Omada to solve that problem? I can't see anything in the (small) log-files. Is there a way to tell in Omada "the connections between these two devices has to work under every circumstance"? I tried some "all-to-all" rules but nothing helped (try and error).

BTW: i do exactly the same with my Wallbox without any problems. I'm really frustrated and thankful for every advice...

Thanks in advance!

Thomas