How do I manage the AP of a surf soho from a Balance 30 (LTE)?

I have a surf SOHO and a balance 30 LTE.
The B30 is the router to the world (2-3 WAN connections), and the SS is the wireless access point, being a local node on the LAN.

I want to use the Surf SOHO to broadcast a number of SSIDs, each on its own VLAN.
I was hoping to use the VLAN management on the B30 to handle all the VLAN settings (incl. IP assignments) via the AP controller tab on the admin pages. Using the VLAN settings on the SS makes them invisible to the B30 (AFAIK).
However, the B30 does not see the SS as a manageable AP - how does the SS register with the B30?
Alternatively, is there some way to set the SS to bridge mode?

You can’t configure Surf Soho as an AP. AP Controller function in Balance 30 was design to manage our AP product. You may consider using AP with Balance 30 for your requirement.

Thanks for the info. I expected as much, but was hoping…