So far, so good. Faster, no dropped connections.
For starters, I got a 30-foot Ethernet cable, and plugged the new router into a port in the back of the old router, and set the new router up closer to the garden. So far, so good.
Of course, I've seen this before, and then the situation deteriorated. And there are literally thousands of posts at Apple Support about fucked up WiFi and the general consensus is that it's Apple, and in particular OS Mavericks. So we'll see how it goes.
However, the variable of me and the tenants using the same router has been eliminated, at least.
Now I am going to go dig up some soil and make a squash mound, assuming I can remember what I did with the squash seeds. Some kind soul reminded me that squash has very short growing season, and so, heck, why not put some more in?
UPDATE Post squash mound: Still good.