Katello server and proxy certificates expired

I have a katello/foreman installation with two foreman proxies.
Today all the certificates used by foreman and proxies are expired and foreman does not talk with proxies anymore.
How can I renew the certificates and fix the communication between server and proxies?

Thank you very much
Kind regards

Foreman and Proxy versions:
foreman v. 1.17.1
katello v. 3.6

Hey @brunetti,

Thanks for your question. @ehelms or @ekohl do you know anything about this?