Thanks, all, for the responses. I’m not sure I understand exactly what’s going on, but…
I have 600 for wlan0 and 1050 for wwan0.
I do have ipv6 disabled on my wifi network and devices.
I checked in Advanced Network Configuration and saw that ipv6 was set to “automatic” for my mobile carrier, so I changed that to “disabled.”
As I said, the mobile account in question is only used minimally, so I can just keep it disabled when I don’t need it on. Of course, I want to understand how to make sure it’s not used when wifi is on, though.