We have 8 Exchange 2016 servers with version CU22, KB5007409. On 2/17 we started getting reports that users could not connect to the ECP portal. On further investigation I found that if I used the server's url (https://server-01/ecp) and connected to the server from my computer it worked for 4 servers and failed for the other 4 (Tried from Different computers and different browsers - Same issue). I know that this was working for all 8 servers. If I remote into any of the problem servers and run the ECP Portal locally it works.
The error message is "Something went wrong. We can't get that information right now. Please try again later".
I just discovered that If I use https://server-01/ecp/?ExchClientVer=15 on the problem server that works. How do i get this fixed so that navigating to https://server-01/ecp/ works. There were no updates to the server since Nov 21 and no changes since.
We ended up opening a Microsoft case. It appears that the Exchange patch we had deployed at the end of 2021 caused the problem on some of the servers which were in a different region - A redirection issue. We just installed the Jan 2022 patch and that fixed the issue. https://support.microsoft.com/en-gb/topic/owa-redirection-doesn-t-work-after-installing-november-2021-security-updates-for-exchange-server-2019-2016-or-2013-9dc8f203-351e-4527-b9b6-794a2c947d44