Where is the CAN bus connector X30 on a W210?
 

X30 is the main connector where all CAN devices tie in.
I have read the pdf file, which says the connector should be in the right door sill area, in the black plastic cable run. Unfortunately it is grouped with the 202 and 208, so the picture may be from another model.
I have checked twice on my '99, and it isn't there. Has anyone actually found it on the 210?

WIS says under door sill cover behind right B pillar.

Thanks, that's the A-pillar, but with the picture I found it. It was buried down in at the bottom and angled so I couldn't see the long side.

I used the Star-Finder app which described it as B pillar but the little red dot was near the A pillar. Glad you found it.