now I'm at 19 (11 in/8 out)
Hmm.. I'm not running thru a tomato router any more.
Let me try that.
Other than that 'something is wrong', what problem with more connections?
Maybe I've been granted honorary node status!
No, I haven't knowingly changed anything.
Tomato has uPnP disabled by default IIRC your new probably has it enabled by default, unless its also some alt firmware. Bitcoin has enabled uPnP by default, thus the new router might have opened a pathway from the outside to your machine as bitcoin core requested.
I imagine thats roughly what you figured from the page as well?