unable to share files through skype for business 2015 between internal and external users

Hi,
on the front end servers of Skype for business 2015, i was getting Errors/informaitons, with event IDs:  41024,41025, 41026
Event: 41024
No connectivity with one of the Web Conferencing Edge Servers.
Edge Server Machine FQDN: server1.domain.com, Port:8057
If the problem persists this event will be logged again after 20 minutes
Cause: Service may be unavailable or Network connectivity may have been compromised.


Event ID: 41025
Connection to the Web Conferencing Edge Server has succeeded
Edge Server Machine FQDN: server1.domain.com, Port:8057
Event ID: 41026
No connectivity with any of Web Conferencing Edge Servers. External Skype for Business clients cannot use Web Conferencing modality.
Cause: Service may be unavailable or Network connectivity may have been compromised.
Resolution:
Verify all Web Conferencing Edge Services in the topology are running, and network connectivity is available.

Errors:
No connectivity with one of the Web Conferencing Edge Servers.
Edge Server Machine FQDN: server1.domain.com, Port:8057
If the problem persists this event will be logged again after 20 minutes
Cause: Service may be unavailable or Network connectivity may have been compromised.

Solution:
add the following key to resolve this issue.
reg add HKLM\SOFTWARE\Microsoft\.NETFramework\v4.0.30319\System.Net.ServicePointManager.RequireCertificateEKUs /v “C:\Program Files\Skype for Business Server 2015\Web Conferencing\DataMCUSvc.exe” /t REG_DWORD /d 0 /f


After adding the above key on the front end servers and restarting the "Skype for Business server web conferencing" service, the above errors were not appearing any more and the issue of file shares etc. was resolved.

https://support.microsoft.com/en-in/help/4023993/ls-data-mcu-41026-41025-and-41024-after-may-2017-net-framework-update