I recently upgraded EPO 5.9.1 to 5.10 and started getting the error in the attached screenshot below which is accompanied by the EPO server completely locking up.  A reboot is necessary to make it functional.  The problem has happened twice in the past week.  SQL and EPO are installed on the same server.

I see this error in the EpoApSvr.log on the EPO server many times when the error occurs: 

20191022123041 E #06036 EPODAL , msg=Unspecified error
20191022123041 E #06036 EPODAL ePOData_Connection.cpp(719): COM Error 0x80004005, source=Microsoft SQL Server Native Client 11.0, desc=TCP Provider: An operation on a socket could not be performed because the system lacked sufficient buffer space or because a queue was full.

I have reviewed the conversation in this forum

https://community.mcafee.com/t5/ePolicy-Orchestrator/ePO-Database-Connection-Issue-DB-Server-Key-Che...

I ran nmap to check the cipher suite on my EPO server and only see the keys shown below.

TLSv1.2:
| ciphers:
| TLS_RSA_WITH_AES_128_CBC_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA256 (rsa 2048) - A
| TLS_RSA_WITH_AES_128_CBC_SHA (rsa 2048) - A
| TLS_RSA_WITH_AES_256_CBC_SHA (rsa 2048) - A

There are no TLSv1.2 keys listed for "TLS_ECDHE"

Someone referenced KB91304 for more info on that, but I'm not able to locate that KB.