I'm not sure why it's 10s; my point was mostly that, once you figure out exactly what part of the connectivity process eats up the majority of the 10 second delay, it'll be much easier to figure out the why.

Since connectivity takes (far) less than 10s on enterprise-grade multi-antenna routers, all that time is being spent in some component that's different between the two classes of hardware. So looking at the difference in BOM between average products of the two classes might be helpful in figuring things out.