Proxy can't connect to the auth server

Ported from the slack support chat

Hello, I’m seeing that Proxy can’t connect to the auth server with the following errors:

/var/log/teleport debug log:
ERRO [PROC:1]    Critical service proxy.init has exited with error Get https://teleport.cluster.local/v2/configuration/name: x509: certificate signed by unknown authority, aborting. service/signals.go:149

It looks like teleport proxy can’t connect to the auth server
because it has already received the certs (from an old install perhaps?)
it’s easiest to delete all proxy data in /var/lib/teleport/* and rejoin the cluster.