It’s been a while since we’ve seen trippy86 — their last post was 3 years ago.
If your My Cloud Home is more than 3 years old, it might be on borrowed time if it has been on continuous duty as a server.
Download the debug_logs.tar and examine the smartdata.log yourself or file a support ticket with WDT to see the status of your hard drive as the slow breathing white LED could be indicative of hard drive failure.
ISP owned routers are updated and reset frequently without user’s knowledge. You can’t know what has happened to the firmware update. Nobody can troubleshoot your router like you can. WDT is not going to give you the answer for another piece of equipment in your home.
It could look something like the last reply in this thread, although the subject is port forwarding, it is similar with UpNP.
The MCH does not need UpNP to be seen locally. Usually one could download the debug_logs.tar by signing into the webapp (browser) and see if the settings can be accessed and debug_log can be downloaded, if not one could also access the log through the MCH ip address. This is all documented in the knowledgebase, search for ‘debug log’.
You should file a support ticket with WDT support even if your device is out of warranty. Have you ever downloaded the debug_logs.tar during the 3 years you have had it in service? What was the last firmware version you are aware you had on the device? Nobody knows the history of your MCH more than you. The reader has no idea whether you had turned it on for one week 3 years ago and then stored it away for 3 years since, for example. These are all the questions a good support person could ask.
Even if the MCH appears offline, it could sometimes be found on the network and thus allow the debug_logs to be downloaded. Over the 3 years, you should have an idea what IP address it was on, if not, try a free software IP scanner which may show you what its IP could be. Then you follow the instruction on downloading the logs. Try with different browsers if it doesn’t download or save the file.
I am sure you know this given your history with the MCH, but for other readers, if the purchase was made from a reputable authorized dealer, one would not have to take it apart DYI and apply any repairs. A simple online claim would have got a refund or replacement for the owner.
Direct from Western Digital, My Cloud Home 8TB refurb. $150, 2 year warranty from All State.
When purchased on sale which it is no longer, this is still the cheapest form of cloud storage hardware anywhere and that is the main reason home users and small businesses alike buy these units.