So I recently upgraded my router and wireless access points at home and thought it would be a great time to change my WPA password because it'd been the same since... too long. Most of my IoT devices moved over without too much hassle except my Mitsubishi mini-splits. These connect to Home Assistant through the awesome Kumo Cloud HACS integration. I knew they would be a pain, since they require 2.4GHz and the wifi modules aren't physically accessible without taking the devices apart so if anything went horribly wrong, I wouldn't be able to reset them easily.
Things went horribly wrong.
Fortunately, after a call to Mitsubishi and a LOT of messing around with the Kumo Cloud app, I'm back up and running without needinng to crack open the units. Here are some lessons learned in case they help others (or me in 6 months!).
- Assign static IPs to the units on your DHCP server. No, really. I know the HA integration doc says it will update the IP addresses when you restart Home Assistant, and it does try, but that doesn't help if addresses change after HA is running or the units fail to update Kumo Cloud with their current address. Both things happened to me, which would cause the mini-splits to show up in the Kumo Cloud app, but not Home Assistant, or sometimes go missing in both. I would've saved myself a bunch of time if I'd just used static IPs from the beginning.
- If you have a multiband wifi access point (and who doesn't nowadays?), create and use an SSID that only supports the 2.4GHz band. These devices will not talk on any other frequency so that can be a source of connectivity issues. I think the Kumo app does a pretty good job of warning about this, actually.
- As of May 2022, the Kumo Cloud app will fail to update the wifi settings on the mini-splits from an Android 12 device like my Pixel 6 ("write error" when it tries). This is apparently a known issue when I called Mitsubishi and has something to do with Bluetooth changes in Android 12. (The app uses Bluetooth to send configurations updates to the wifi modules inside the units, I learned.) I had to switch to my Fire tablet to get anything working.
- When the wifi config failed to update because of the previous issue, the units fell back into a pairing mode. This is not obvious because there's no indication of it in the customer-accessible parts of the Kumo Cloud app and no visible lights on the mini-split. That's when the helpful Mitsubishi tech introduced me to the all-powerful Installer Settings section of the app. God mode! 😎 It's locked with a super-secure static PIN of 9999. I needed that for the rest of this bloody exercise.
- From Installer Settings, you can go to the site menu and an Add indoor unit button shows up there. This allows you to re-add any units that are currently in pairing mode if you move close enough to them. Don't worry if you're trying to add a unit that already exists in the app, it will overwrite the old config by matching its MAC address. With this, I was able to see more details about the config update process, and for most of the units, this was sufficient to get them connected on the new wifi. But a couple of stubborn ones failed to complete all steps of the reconfiguration. Bluetooth hiccup perhaps. For those, I had to go through the same process multiple times and/or click on the unit names in the app and reconfigure their wifi through the normal customer mode interface. Eventually, they all connected. I then needed to restart HA for them to show up again, since their IP addresses changed.
- After all this, one stubborn unit worked fine in the Kumo Cloud app, but HA refused to see it. I looked in the
kumo_cache.jsonfile that the integration generates at startup and I could see that the IP address was wrong. But no amount of deleting the cache file and restarting HA would fix it. Re-adding the unit to the wifi for the umpteeth time also didn't help. So back into Installer Settings. I clicked on the unit there, and under Advanced, there is a Refresh Setttings option. Bingo! This resynchronizes the state of the device with Kumo Cloud, apparently. Clicked that, restarted HA again, and finally, it shows up!
Ugh. Wait a pain. Lessons learned.