401 Errors when using Outlook behind load balancer

Question

401 Errors when using Outlook behind load balancer

yyztech 1

Hi,

We have setting up a hybrid environment where the users(outlook) uses will hit the a gcp load balancer first and then to our on prep exchange 2019 server. The bigger picture is to use WAF for OWA for end user. We haven't enabled WAF so far. The service is breaking at load balancer level.

When using the load balancer, we are getting 401 error for any/all mapi communication. I have set all IIS directory to accept basic authentication.
I do see error in the IIS logs..

Any idea whats causing this error 401?

Aaron Xue-MSFT 2,601 Reputation points Moderator

2022-03-15T05:39:43.41+00:00

Hi @yyztech ,

Thanks for posting in our Q&A.
Since this issue is more related to the gcp load balancer. But in this forum, we only discusses Exchange on-prem services issues.
I recommend you to contact with Cloud Load balancing team to get accurate help.
yyztech 1 Reputation point

2022-03-15T13:52:15.147+00:00

Hi @Aaron Xue-MSFT

Thanks for replying. I get it, even though the error is in IIS logs of exchange server, this is related to GCP load balancer.

Many thanks!