there's about 30' of ductwork before the blastgate to the
TS. Then there's a 6' hose to the TS.

Too long a run for a small dust collector. That is one problem. I doubt you
want more than 20 total feet of run, nor the 36 you currently have.

My jointer €“ planer and thickness planer are
almost as far from the DC as the TS is and the DC works great for
them.

They create much larger shavings, so it's easier for the airstream to take them
(I know that sounds contradictory, but it's not, in reality). Tablesaw dust is
very fine, and it takes a lot to capture it. Also, the jointer hood is closer
and more surrounding of the cutter. A tablesaw dust pickup is really poor; you
are depending upin the force of the blade to push the sawdust down to where the
airstream will claim it.

Also, make sure you are using a guard with air pickup. Most of the dust in
ripping will actually push back on you before it even gets intot he cabinet, so
even a 5 hp Oneida can't get it then.