Cannot connect to SunPower PV6 - Tips? Things to try?

I have had this issue. In my case it was due to a failed firmware upgrade. I opened a ticket with Sunpower corporate, it required the installer to come out to force an update on the PVS6 as the firmware update had failed. I'm not exactly sure what he did to force the update, but I'm guessing it wasn't much because he was not here very long. You could try a hard reset (powering off system). If that doesn't work, maybe asking Sunpower and/or your local installer if there are any steps you can try yourself to reboot/reset the PVS6. However, I'm guessing Sunpower has already asked you to try a reboot as they asked me to try that first and then wait 24 to 48 hours to see if that fixed the problem (it didn't). Once the problem was fixed, it started reporting again, but did not provide any data during the period it stopped reporting (despite Sunpower and the installer saying it would)

You could try hard wiring your PVS6 and let Sunpower know and maybe they would open a new ticket? I think the newer versions of the PVS6 eliminated the ethernet port, but there are specific usb ethernet adapters that have been proven to work with the PVS6. The 202023 by cable matters is one of those.

If you are technically inclined, there are alternative ways to do self-monitoring from a PVS6 using an old router or travel router or using a device such as raspberry pi. This really became popular once the separate panel level monitoring website was eliminated a few years ago (there is mention of it on this site).

Sunpower support was never the greatest, but with bankruptcy concerns floating around for them currently, it may even be worse now.