internal GTM integrate with external LTM

To explain the issue in more detail I included some more pics and graphs. This is the lab architecture both F5 Big IP VMs are located in the same network segment.

The external LTM has connectivity to both internet connections. The internal LTM / GTM combo needs to resolve DNS requests and know the link status of both Links and virtual servers. So I was thinking to integrate the internal GTM with the external LTM using Iquery.

The server link is active configured on the internal GTM using the external Self IP 192.168.1.120 and Iquery traffic is flowing between both F5 devices.

So that seems to work properly, but the thing is that the internal GTM is unable to determine the status of links and virtual servers nor discover them automatically. If I configure one manually its becomes unavailable.

But the virtual server is indeed available on the external LTM.

Analyzing the Iquery traffic using Iqdump I do see active traffic.

Someone any idea what to do to solve this issue?