(Author here) I didn't forget, it just didn't seem like the most likely problem.
Like I said in a reply to a sibling to your comment, the gear was ~10yrs old at the time and had been working fine until then. It was perched in a very inconvenient spot because it had to "look around the corner" of the building, so checking the line of sight wasn't just a case of looking out the window.
I went in order of "most likely to be the problem, weighted by how easy they were to check." This is a debugging strategy that has served me well, and I don't regret using it that time either.
But rain is more obviously related^ to a point to point link than aging hardware or some kind of bad update?
(^though of course the improvement is surprising! I assumed there was antennae involved, whether point to point or LTE or whatever, just from the title. The story to me was from the outset why's it better not worse in rain.)
But it could be rain helping close a circuit on a rusty antenna connector port. Or rain improving the grounding of some neighboring circuit that otherwise drains through the metal scaffolding the antenna is attached to. Or rain attenuating a neighbor's own Wi-Fi that otherwise might have been aggressively transmitting on the same channel as our units.
The rain and the Wi-Fi devices were clearly related. How they were related, was not clear. Aging hardware rusts, breaks, gets yanked around or unseated or pulled out of the ground, or has water enter in places where it shouldn't be.
I was already running diagnostics on everything to figure out which devices might be faulty (local AP, local bridge unit, local antenna, remote antenna, remote bridge unit, remote switch, remote modem/router, upstream connection to ISP) so checking for "update gone wrong" was a 3 second job: I was already in the admin UI, so check logs, nope, no recent updates, done. I'd rather spend 3 seconds checking something that probably isn't the problem but I can know for sure in 3 seconds than risk climbing precariously up a scaffold 30ft in the air only to realize it was just something I could have solved at a keyboard instead.
Risk/reward. Low risk, low reward is okay too if it's super fast and already on the way.
Like I said in a reply to a sibling to your comment, the gear was ~10yrs old at the time and had been working fine until then. It was perched in a very inconvenient spot because it had to "look around the corner" of the building, so checking the line of sight wasn't just a case of looking out the window.
I went in order of "most likely to be the problem, weighted by how easy they were to check." This is a debugging strategy that has served me well, and I don't regret using it that time either.