Results of file search can't be opened

Hello,

I can't open results of searching in any network location on Windows Server 2012 R2. Files are found but for unknown reason I can't do anything with them. Can't use click or right click, nothing.  Just white icons. If I search directly on the server result is the same.

I can fix this by rebuilding file index on the server but it will work only for few hours.

Event Viewer events about "Search" worth pointing out:

1. Event id 3036 - Crawl could not be completed on content source  <winrt://{S-1-5-21-702083037-4092738604-xxxxx-6164}/>. Context: Windows application, SystemIndex catalog. Details: The parameter is invalid. (HRESULT : 0x80070057) (0x80070057)

2. Event id 10023 - The protocol host process 2636 did not respond and is being forcibly terminated {filter host process 4624}.

I just don't know if (or how) it might be correlated. I got valid search results. Files are there but Windows Explorer refuses to open them.

Same on clients with Windows 10, 8 and 7

Thanks for any help.