Likely the warnings are not “real” but simply a result of Docker issues when container can not access services running on the host network (like AiO accessing your reverse proxy).
My best solution for this was to duplicate the split-brain DNS config inside Docker so all internal communications (e.g. from Nextcloud to Collabora) doesn’t go outside of the system but hits the reverse proxy internally. Look at Probably DNS help with NC Docker + Collabora + Wireguard tunnel