I have recently configured rpc over http with NTLM auth in our staging env with exchange 2013 (enterprise) and AD 2012R2, by setting MapiHttpEnable $false at the exchange org level, to have it match our production.
From an internal env (within the datacenter network -same network as the exchange servers using virtual desktop) outlook profiles are able to be created successfully, and outlook connects using rpc over http with ntlm.
however, when connecting to the env on a physical machine through vpn to the staging env, and creating an outlook profile using auto discover, with outlook 2013 and outlook 2016, the following message displays: 'an encrypted connection to your mail server is not available, click next to attemp an unencrypted connection'. Tried this on multiple machines, and same issue.
When i click next, it fails. Autodiscover is setup correct, because before when mapi over https was enabled on exchange servers, outlook was fine on physical machine connected via vpn. Outlook was able to successfully make a connection via autodiscover. However now it is not. In between we have load balancer, and firewall.
Please assist to troubleshoot this issue.
Thanks in advance.