WD Sentinel DX4000 remote web issue

e have an install of Server 2008R2 Essentials on WD Sentinel DX4000  which is showing the error below when trying to access Remote Web Access.

When accessing Remote Web Access by going to https://remote.abc.com/remote and logging it, the following error is displayed:

Everything was working fine before this error and i didn’t make any changes


Check if the ports 80 and 443 are not blocked and confirm that the certification still valid. 


I have checked the certifcates and ports both are okay