Nextcloud Talk / coturn certificates

I’m going to setup an own turnserver using Debian 10 and coturn. I followed the howto in this forum.
For my Nextcloud 17 server I bought an PositivSSL certificate from Comodo. Now I have the following files:

  • key
  • crt
  • ca-bundle

I converted the files into pem format. Coturn has the configuration entries cert, pkey, CA-file. So

cert -> crt
pkey -> key
CA-file -> ca-bundle ???

Do I need ca-bundle file from Comodo in the coturn configuration?

Any help is welcome!

Kind regards, go4ncloud