I'm running a custom PHP/HTML application on Windows Server 2012 R2, IIS 8.5 on my company local intranet (server and clients are at the same location, no VPN, or whatever, only a gateway between VLANs). This site/application can host different files type and offers them to HTTP download.
On HTTP GET request (in order to download these files on client) we randomly gets some sc-win32-status 995, and the download fails:
2017-11-03 06:27:54 10.214.72.26 GET /tpm/lecon/fichiers/LP-2859.docx - 80 - 10.214.77.6 Mozilla/5.0+(Windows+NT+6.1;+Win64;+x64;+rv:56.0)+Gecko/20100101+Firefox/56.0 http://amtblieapp1.xxx.xxx/tpm/lecon/afficher.php?id=2859&aLire=oui 206 0 995 18951
After a few page refresh it sometimes works for the same file.
It seems that the server resets the connection immediatly after the GET request, see this wireshark dump from the client (Client : 10.214.77.16; Server : 10.214.72.26):
41 5.466337 10.214.77.16 10.214.72.26 TCP 66 58119 → 80 [SYN] Seq=0 Win=8192 Len=0 MSS=1460 WS=256 SACK_PERM=1
42 5.467774 10.214.72.26 10.214.77.16 TCP 66 80 → 58119 [SYN, ACK] Seq=0 Ack=1 Win=8192 Len=0 MSS=1460 WS=256 SACK_PERM=1
43 5.467858 10.214.77.16 10.214.72.26 TCP 54 58119 → 80 [ACK] Seq=1 Ack=1 Win=65536 Len=0
44 5.468186 10.214.77.16 10.214.72.26 HTTP 571 GET /tpm/lecon/fichiers/LP-2859.docx HTTP/1.1
45 5.478248 10.214.72.26 10.214.77.16 TCP 1514 80 → 58119 [ACK] Seq=1 Ack=518 Win=131328 Len=1460 [TCP segment of a reassembled PDU]
46 5.478295 10.214.72.26 10.214.77.16 TCP 56 80 → 58119 [RST, ACK] Seq=2922 Ack=518 Win=0 Len=0
47 5.478346 10.214.77.16 10.214.72.26 TCP 54 58119 → 80 [ACK] Seq=518 Ack=1461 Win=65536 Len=0
I disabled static files compression in IIS, but it didn't help. This problem never occurs with php,css,htm,js,... files, only with documents. MIME types are correctly set-up in IIS.
I've found this related question but unfortunatly no clear answer there.
What could lead to this issue ?
