I have share a debug log from PHD2 in PHD2 forum.
And I have just get a message from Patrick Chevalley concerning connection issue.
Apparently some driver modifications are needed.
Is there a standard way to ask for this modification?

“The problem is this INDI driver do not implement the required pulse guide command.
It only report a TELESCOPE interface instead of TELESCOPE|GUIDER, and PHD2 never receive the properties TELESCOPE_TIMED_GUIDE_NS and TELESCOPE_TIMED_GUIDE_WE so it cannot accept to connect as guide mount.
This explain why it connect as AUX mount because in this case the mount guide command are not necessary, only reading the pointing coordinates.

You can ask the developer of the driver if it is possible to add this guiding command. Otherwise the only solution is to use a ST4 cable from the camera. “