Cannot connect to vault

Hello everyone.
I’m new to this whole topic, in fact new to selfhosting at all.
i am a complete newbie, nevertheless i hope someone is willing to help me out.

i have installed on my synology / docker vaultwarden/bitwarden.
it is running. i can connect via my ios devices.
i have created a test login/password and it is being synced between my phone and ipad.

now i want to login via my Android device, windows app.
this is not working.

windows app give me an error 405
and the android app we were unable to proccess your request please try again or contact us.

does anyone have an idea what is causing this?

thanks for all your help