Device Trust issue

When setting up device trust you need to enter the mgt IP of the peer guest device to establish the initial trust relationship. Also you do not need floating IPs on the isolated HA, as each device will talk to the peer directly no other traffic will use the vlan.

Follow this procedure and see how you go...

https://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/bigip-device-service-clustering-admin-11-5-0/2.htmlconceptid

cheers