Very short answer: That is not possible.
Very long answer:
You will have to evaluate if disabling "Protected Mode at startup (Preview)", turning "Protected View " off, and /or disbaling "Enhanced Security" would be a workflow that your organization is willing to put up with as a workaround; there's no cure for this.
This is an ongoing topic with no solution in many threads in these forums and it can be traced ack to 2012 with different versions of MS Windows Server acting as a DFS.
The use of Group Policy in cross domain configurations also doesn't fix this.
So I've been thinking if disabling the Internet Explorer's browser integration with Acrobat or Reader completely (and set another Chrome-based browser as default via registry settings) would circumvent the 32bit sandboxing barriers that Adobe Reader was natively designed to enforce, specifically with Internet Explorer integration (which also has a direct relationship with Windows Explorer). If I was in your shoes, consider how to move such PDFs as trusted files to privileged locations.
But all of this has been discussed before in other threads. Simply put : Not possible!
The securtiy sandboxing will only limit the Adobe Reader process to two instances; one for when the same file is accessed through the web browser (less restrictive, less secured), and one instance when the same file is accessed via DFS shares (super restrictive, all security sandboxing is enforced).
While Acrobat Pro has the ability to call for trusted functions via privileged or non-privileged context , Adobe Reader doesn't by default. It is completely restricted. In fact , making Adobe Reader more asecure than Acrobat Pro.
That being the case, you would need to find a way on how to escalate the context of the requesting permissions.
See if you get lucky by exploring and analyzing the Acrobat Application Security Guide:
If you do find a solution it would be great if you can report back to these other discussions (seems like everyone is still waiting):
But you can go ahead and sift through all of these other fossilized discussions:
As you can see in most of the links above, Adobe has been working too on trying to get a fix for this via updates.
So short answer: Not possible.
Seems like the issue might've been fixed.
Please check if your Acrobat is updated to its lastest version 2020.012.20041 which was releasaed about 2 days ago.
Even though your inquiry is slightly different from the discussion in this thread:
today an Acrobat user reported (see last post in the link above) that updating to the latest version seems to address the issue when a user double clicks or tries to open more than one PDF from a DFS server.
I checked the release notes and I don't see any particular information that addresses that issue though, but nevertheless, give it a check.
If you've updated to the latest version already and the issue persists disregard this message.
But if you haven't updated yet , here's the linkk for the August 2020 update: https://www.adobe.com/devnet-docs/acrobatetk/tools/ReleaseNotesDC/continuous/dccontinuousaug2020.htm...
See if today's your lucky day.
Sorry to hear that you are facing issues with Adobe Reader.
A new version of Adobe Acrobat/Reader DC is now available. Please update the application to the new version and see if that works. Go to Help > Check for Updates.
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