The external OWA access to Exchange 2016 stopped working over the weekend.
We are running a small internal Exchange 2016 installation with 25 users. The external owa site has been working until recently - last 5 days. The owa and outlook access are working internally within the local environment, but not from the internet. The exchange server claimed to have issues with ldap access to the adcontroller in the event log, but shows connections to ldap with the netstat command.
The IIS shows the site being active with the correct certificate attached. Again, nothing changed.
I have rebooted the AD controller (first) and the exchange server (second) with no change in connectivity. We have not installed any updates or new software in the last month. The firewall on the exchange server has been turned off for testing.
The wan access firewall (Sonic wall) has also been rebooted, and has all other access working.
Internal connections work, external do not. I suspect it is related to LDAP/IIS/OWA but do not know how to proceed next.
Thank you, in advance,