CHALK Session terminates before people can join

Hi,

I have been trying to set up a chalk session with my colleague, but the Session closes before the connection is fully set up, he can't see my screen, even when I had finished scanning the environment. Then the Session automatically closes.

The  https://networktest.twilio.com/ test shows no problems.

Are the PTC servers working? (we are in Switzerland)

Thank you for your quick response,

Alex