I've been having this problem since we upgraded to GW 2014 R2. I now have WebAccess 2014 R2 SP1 and I still have the same problem. It's intermittent for many users on a single post office.

I have 6 post offices configured in the webacc.cfg. One post office will give a "9505 Your post office is unavailable" to a hand full of users it does not like. Some of them can log in if they use their fully qualified GroupWise address, domain.postoffice.username I've got a few users who can't login at all.

Here's what the WebAccess log shows for a failed user login attempt, which gave them a 9505:

13:07:38, <SOAP>, -, INFO, MUser, Login
13:07:38, <SOAP>, -, INFO, MUser, Unable to connect to the POA @

Now, I have 5 post offices in my GW domain. The one we have trouble with is a post office in another domain that is connected via GW External System Sync. This other domain has always used our GWIA and WebAccess servers without issue.

My webacc.cfg file has their POA address and SOAP port in correctly just like all our other post offices. 90% of the users in this troubled post office can login successfully every time through WebAccess. There's just 15 or 20 users that have this problem.

Has anyone else seen this? I've worked through the TID's that are for 9505 through WebAccess login with no change in function. I was hoping upgrading to SP1 was going to fix it but it has not.