Shelly iOS App Causes Frequent IMSAI-8080 Resets

[halfpress]

I recently started installing Shelly units in my network that do power monitoring at the outlet level. They are ESP32 devices which I believe is also true of the IMSAI replica.

My IMSAI is on in my office 24/7 as part of my decor and I recently kept hearing a random beep and then later noticing my unit was not in a running state (no flickering of the lights). After a while, I came to realize that the Shelly iOS app, which does an MNDS query at regular intervals looking for unconfigured Shelly units, was causing the resets.

I can repeat it with regularity. It's not on every launch, so I don't know yet what the precise trigger is... but every few launches of the app will cause my IMSAI to go black, beep (I believe that's the S132 unit) and reboot.

This is the app. I suspect anyone could run it to try this even without Shelly devices since the action causing it is their scan for newly installed units:

https://apps.apple.com/app/id1660045967

Again, it's not on every launch... but often enough that it wasn't hard to recreate.

I've done some packet captures and I see a flurry of MDNS queries from my iPhone and I do see that it will, in some cases, hit a URL (resulting in a 404) on the IMSAI... but the http query doesn't seem to be the problem. I'm guessing something in one of the MDNS multicasts is triggering a freakout on the IMSAI?

Not a crisis... just thought I'd share in case it was easily solved in the future. Mostly an annoyance. :)

Best,

• Aaron