Chatbot working on Telegram on iOS, not on Android

Hey there, I created a bot which is running on my local machine for now. I use ngrok to make a port visible and integrated it to Telegram. On iOS and the MacOS-App i can chat with this bot like I expected to. A friend with also an iPhone can chat to this bot as well. But on Android this is not working. After starting the bot and starting a dialogue, there is no response and I get 500 Internal Server Error.

Is there anyone else having this problem? Any suggestions how to fix this?