I'm running LibreELEC 8.2.2 on a Raspberry Pi 3, updater is configured for manual update and notification.
I found that since a while - unfortunately I can't say exactly since when - I have not received the "Update available" notification anymore. There is definitely none for 8.2.3. I reboot my Pi regularly, and also have it running for a while regularly. I remember from before that the update notification used to appear a few seconds after booting into Kodi.
Using the LibreELEC config addon and manually listing the available versions there, including download for update, works correctly.
I can't find anything in the debug log pertaining to update check or failure thereof.
Using a packet sniffer and Google, I found that the update check URL for me seems to be as follows:
where "[My-ID]" is, according to the Wiki, the MD5 hash of my Pi's primary NIC. That request is sent at least on every boot of my Pi.
Very interesting: When I enter that URL into Firefox (or use urlquery), a blank page (or blank file if I use wget on Linux) is returned. I'm assuming the URL should return something like Google has cached for a similar query?
This is Google's cache of https://update.libreelec.tv/updates.php?i=4794f77050a45f7e0023677e07eb1a46&d=LibreELEC&pa=Generic.x86_64&v=8.2.0&l=1. It is a snapshot of the page as it appeared on 30 Dec 2017 00:03:17 GMT."
{"data":{"update":"LibreELEC-Generic.x86_64-8.2.2.tar","folder":"releases","host":"","MD5":"58a7cdfdde2359882c5a24c641867db0"}}
As I said, the methods I used returns an empty page, whatever I put into the parameters after updates.php. Maybe the detection PHP script on the server is broken somehow?
For me (and the Google NS, urlquery.net and tcpiputils.com) "update.libreelec.tv" resolves to 165.227.152.174 which is hosted by DigitalOcean and apparently located at the or close to the DE-CIX in Frankfurt. The certificate presented by the server is issued by LetsEncrypt and was created January 20th 2018.
SSL Server Test: update.libreelec.tv (Powered by Qualys SSL Labs)