Apache logs filling with 408 errors on upgrade to CF2016

[Terry_2011_]

We upgraded to CF2016, Red Hat 7 and are suddenly getting this in our apache logs:

xx.167.xxx.6 - - [18/Jul/2017:09:28:49 -0600] "-" 408 - "-" "-" "-" 80

xx.167.xxx.6 - - [18/Jul/2017:09:28:49 -0600] "-" 408 - "-" "-" "-" 80

Lots of 408 errors with no URLs associated to them.   Coming from a large number of IP addresses, including my own.

Does anyone have any idea what might be going on here?   No one is reporting pages displaying 408... but these messages must be in our logs for a reason.

Thanks

[haxtbh]

Did you change the apache config?

408 is request timeout which means the client has connected but not sent any data before the required time

[Terry_2011_]

We did upgrade Apache too, but Timeout is at 60 seconds.   The site is blazing fast, so I'm not sure why my own connection is generating timed out requests within 60 seconds?