Topology Question RE: STP

[superjet]

I’ve got an AiMesh setup with 4 AC68Us and an old N66u that just works like a switch, no wireless enabled. A multi layer Cisco switch ties the whole network together.
I’m looking to add redundant links due to running cables for other reasons anyways. There doesnt seem to be any options in the STP configuration settings of the main AiMesh router, but it is enabled. Is that STP or RSTP or something else?
Running new cables anyways, figured there’d be benefit to redundant links.
In the picture the black lines are the current links, and the dotted red lines are the proposed links.

All ASUS devices running proper Merlin with latest stable for each device. Cisco switch has full network stack features enabled

 

[Morris]

It must be RSTP or STP with zero delay as when you connect a workstation to the switch with spanning tree enabled there is no delay before traffic flows. Make shore to enable spanning tree before connecting the cables.

Morris