F5 LTM upgrade from Version 10.2.4 to Version 11.6.0 HF6

If you have not already done so, you should check in with F5 Technical Support about upgrade support. There are many considerations when upgrading from v10 to v11, especially to v11.6 and especially in the area of configuration file incompatibilities. (See https://devcentral.f5.com/questions/upgrading-from-version-10-to-version-11-synchronization-configs-lost for other experiences.) For example, in v11.4, support for the HTTPClass profile was dropped in favor of using Local Traffic Policies. (See https://support.f5.com/kb/en-us/solutions/public/14000/400/sol14409.html for a little guidance.) This manual chapter - https://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/tmos-active-standby-upgrade-11-1-0/1.html - provides a high level overview of the upgrade process and, while it's a start, it's not indicative of all of the upgrade considerations.