Endpoint Protection

What are the Windows versions that are supported in SEPM 12.1.7?

12.1.6 MP5 is the latest version. Release notes are here:

Symantec™ Endpoint Protection 12.1.6 MP5 Release Notes

Windows is supported all the way up to Windows 10

Desktop SEPM
■ Windows XP (32-bit, SP3; 64-bit, SP2; all editions except Starter and Home; all patches applied, including Internet Explorer)
■ Windows 7 (32-bit, 64-bit; RTM and SP1; all editions except Starter and Home)
■ Windows 8 (32-bit, 64-bit)
■ Windows 8.1 (32-bit, 64-bit)
■ Windows 8.1 update for April, 2014 (32-bit, 64-bit)
■ Windows 8.1 update for August, 2014 (32-bit, 64-bit)

Server based SEPM
■ Windows Server 2003 (32-bit, 64-bit; R2, SP1 or later; all patches applied, including Internet Explorer)
■ Windows Small Business Server 2003 (32-bit; all patches applied, including Internet Explorer)
■ Windows Server 2008 (32-bit, 64-bit; R2, RTM, SP1 and SP2)
■ Windows Small Business Server 2008 (64-bit)
■ Windows Essential Business Server 2008 (64-bit)
■ Windows Small Business Server 2011 (64-bit)
■ Windows Server 2012
■ Windows Server 2012 R2
■ Windows Server 2012 R2 update for April, 2014
■ Windows Server 2012 R2 update for August, 2014

SEP client
■ Windows XP Home or Professional (32-bit, SP3; 64-bit, SP2)
■ Windows XP Embedded (SP3)
■ Windows Vista (32-bit, 64-bit)
■ Windows 7 (32-bit, 64-bit; RTM and SP1)
■ Windows 7 Embedded Standard
■ Windows 8 (32-bit, 64-bit)
■ Windows 8 Embedded (32-bit)
■ Windows 8.1 (32-bit, 64-bit), including Windows To Go
■ Windows 8.1 update for April, 2014 (32-bit, 64-bit)
■ Windows 8.1 update for August, 2014 (32-bit, 64-bit)
■ Windows 8.1 Embedded (32-bit)
■ Windows 10 (32-bit, 64-bit; RTM and November Update (2015). Operating system (desktop)
■ Windows Server 2003 (32-bit, 64-bit; R2, SP1 or later)
■ Windows Small Business Server 2003 (32-bit)
■ Windows Server 2008 (32-bit, 64-bit; R2, SP1, and SP2)
■ Windows Small Business Server 2008 (64-bit)
■ Windows Essential Business Server 2008 (64-bit)
■ Windows Small Business Server 2011 (64-bit)
■ Windows Server 2012
■ Windows Server 2012 R2
■ Windows Server 2012 R2 update for April, 2014
■ Windows Server 2012 R2 update for August, 2014 

The strange thing is that when I did the upgrade this morning it came up with a error/notice that Windows XP and Windows 2003 need to have SSL (I think) turned on or it wont be able to connect to the SEPM. It gave me the list below

https://support.symantec.com/en_US/article.TECH225689.html

You need to enable TLS on your XP and Windows 2003 clients

A warning appears to enable TLS on Windows XP or Windows Server 2003 when upgrading SEPM to 12.1.6

However this applies only if you have HTTPS enabled for client communication. If you don't use HTTPS for client communication you can ignore this and no further action is needed.

The latest SSL vulnerabilities were patched in the latest 12.1 RU6 MP5 but would need to be enabled to allow the SEPM to work. 

We use port 8014 so this can be ignored?

As long as HTTPS isn't configured then yes. 8014 is HTTP unless you configured otherwise. HTTPS uses 443.

You can verify by checking here:

Enable HTTPS client-server communications

 But yes, sounds like you can ignore.

SEP 12.1 RU6 MP5 is the latest version. 

Keep this below article handly it provides all the SEP versions release notes, fix notes & System requirements details.

https://support.symantec.com/en_US/article.TECH163829.html