I know this sounds like a support issue, but I suspect it is something else entirely. Please let me explain.
Once I learned that Enphase was converting Envoys from 5-minute reporting to 15-minute reporting, I decided to restrict the access my Envoys have to connect to the "Mother Ship" to only 30 minutes each day. With those settings in place in my router I have managed to maintain 5-minute reporting with the only inconvenience being that I have to wait until the following day to see data on Enlighten.
That is, until last night. Last night, my Envoy-S uploaded a bit of yesterday's data over HTTP, but then it decided that it needed to make contact via HTTPS, which it was unable to do. It stopped uploading over HTTP and only tried this HTTPS request from that point on.
This morning, I noticed that I only had a couple hours' data from yesterday and decided to have a look. When I noticed the blocked HTTPS requests, I gave the Envoy-S access to only that port temporarily. Then I started getting requests to communicate over HTTP again, so I switched it back to allow only HTTP. At that point, it became "happy", in that it was not making any denied requests anymore, but it refused to upload any data to enlighten.
As a result, I do not think the unit is broken, but rather I think it was told to do something that precludes it uploading data. I suspect this may be the result of a recent firmware update I made to the unit via the Installer Toolkit from version R4.6.30(1b8107) to R4.6.42(8854d7).
But I have another Envoy-S and I never update the firmware on both of them at the same time, just in case. That Envoy-S is still at version R4.6.30(1b8107), so I will swap it in overnight to find out if the old firmware allows me to continue uploading at 5-minute intervals or if they can manage to stop that one also, even with the older firmware.
It will likely take a couple of days for this experiment to play out. I'll let you know what happens...