Multiple requests hitting SQL database

I have a bit of strange issue and I am hoping to rule out the F5 as a cause....

I have a web based application that links to a SQL database via an F5 for load balancing. The strange activity we are getting is that when using windows 7 and IE11 if a request takes longer than the 5 minutes to return from the database side (5 minutes is the F5 idle timeout time) the time out kicks in and kills the connection and the client receives an error message as expected... however when the same thing happens using windows 10 and IE11 it doesn't die but instead it spawns a new SPID on the database side meaning that every 5 minutes until the data is returned to the front end (via the first database SPID that was created) a new SPID is created on the database. I cant see how the F5 can do this and why it would act differently between OS's other than W7 &IE11 uses http 1.1 and W10 & IE11 can use HTTP2.0 , I personally think it is how the app server interpreters the connection keep alive but I need to rule out the F5...

Does anyone have any thoughts?