CLI Configuration utility -ERROR: route_mgmt_entry count is 5

looks like this is expected behaviour and the config utility doesn't like it when you have an existing non-default mgt route already configured and you then use config. IF you removed the non-default mgmt route I expect you could then use the utility.

cheers

ID 419733

BIG-IP systems configured with additional non-default management routes via static, OSPF or other protocols might post error messages. The problem occurs when multiple management interfaces are defined. The system might post route_mgmt_entry count errors during the operation of the /usr/bin/config script. Workaround: You can use an alternative method exist to configure the mgmt address and default route: GUI, iControl, tmsh, and configuration file load.