Yes, it’s not a competition, but if you have a line of sight network connection and the network only works when it’s raining, the obvious thing to check is that line of sight.
I didn't think to check the line of sight because I was primed by the fact the bridge had been running fine for 10 years. With networking gear that old, it seemed more likely that a device/cable/power brick had just gone bad with age.
Also, the antenna is on some metal scaffolding propped out 6ft past the edge of our balcony, because it needs to "look around the corner" of the building. It's 30ft in the air, and checking the line of sight involved climbing up there. It certainly wasn't the easiest nor the likeliest thing to check, so I didn't check it first.
Multiple people in the comments just here on HN have mentioned having weird situations caused by routers that had gone bad. I imagine most of their routers weren't 10 years old when they started acting up. How old is your router?
