Issue: undertook a clean install of exchange server 2019 on a windows server 2019 core install (it's a hyper-v infrastructure and the all servers are VMs). Everything was fine as i could log in using the admin account in my AD so i left it alone after installation as i was in no rush to get it up and running e.g. OWA, etc
however, since Microsoft security announcements I undertook windows security updates over the pass week (playing catch up, installed the server and exch in june), however now when i go to https://FQDN/ecp i cannot login using the admin AD accounts default (administrator) and domain specifically created some years ago and all other servers can use the AD Admin login details fine.
Question: what can i do to check exch support on AD Admin accounts? Do I need to reinstall? anyone else had issues with exchange since updates?
My Options: Fail safe and drastic
(1) restore an old check point which I created in June, so will not have the latest updates which is fine and if that works then i know windows updates have crashed my exchange, bad Microsoft but not unexpected.
(2) check AD Admin accounts to make sure their exchange compliant (my first choice) and/or create new user and add to the ECP admin
(3) complete reinstall of OS, fully update, then install exchange again and see what happens (fail safe last man stand resort)