Hello
Are these systems virtualized ?
Does the parameter INBOUND_CONNECT_TIMEOUT fix your issue ?
Are there network errors reported by other tools on these systems ?
Did you performed niping test as requested by support ?
It's surely not an incompatibility between 11.2.0.4 & Win 2012R2 as both SAP (check the PAM) & Oracle (http://www.oracle.com/technetwork/database/windows/tech-info/sod-oracle-db-win81-win2012r2-2088197.pdf) has validated them.
Have you tried deactivating TCP Chimney Offloading & RSS (Receive-Side Scaling) ?
These parameter could cause network problems on older Windows versions.
Its easy to change, just need a reboot to be active.
You can check if they are active with:
netsh interface tcp show global
and disable it with:
netsh interface tcp set global chimney=disabled
netsh interface tcp set global rss=disabled
You could also try changing "Receive Window Auto-Tuning Level"
netsh int tcp set global autotuninglevel=disabled
Regards
1519484 - How to analyze network disconnections shown in system log (BC transaction SM21)
Also, we have found a lot of issues with some new features as the Scalable Networking Pack aka. SNP (TCP Chimney Offload feature, RSS, and NetDMA). In particular, we always recommend to disable the "TCP Chimney Offload" feature option on your NIC. In order to do so, you can run from a command prompt “netsh int ip set chimney DISABLED”; run “netsh int ip show chimney” in order to know its current status. Then, reboot the system (it is mandatory!). Please, check points 6 to 8 in the “Solution” section of note 392892 (MS KBA 942861), also if your database is other than MS SQL Server.
http://blog.wapnet.nl/2014/04/windows-2012-r2-unstable-internet-connection/