The server was unable to save the form at this time. Please try again.
seems to be a well known error in sharepoint 2013 with aggressive mode of fixing it. Primary solutions told by many posts were
- restart SharePoint Search Host Controller due to RAM issue
- web browser extension ...
unfortunately on our 7 servers farm with enough RAM (after a check), what should be done ? iisreset brought nothing good.
In our situation, only Central Administration (CA) web application was impacted, which is the only NTLM one in our farm.
It appears that the root cause was because, due to VPN/DNS reason, I was accessing the central administration by IP address rather hostname. Connecting directly with Remote Desktop Manager (RDP) on the server and using iexplore with hostname, I was able to save my item. Nevertheless, as soon as it was done, I was then able to save the item when accessing CA through VPN.