OSMC cannot install add-ons (cannot connect to network)

Hello everybody, I know that the issue might sound familiar to you guys but it may be not.

I recently formatted Raspbian to install OSMC on a Raspberry Pi 2 model B and after the full installation and the initial settings were provided I noticed that there are no add-ons available. When I try to do Install from repository it says “could not connect to network” even though I am connected to internet with an ethernet cable.

I also checked this previous topic

This topic proved somewhat useful to try to help myself to understand the problem but I could not fix it yet.

What I know so far:
-The device is connected to the internet

Here is the full log http://paste.osmc.io/bufusenafe

Thank you in advance

01:38:01  17.783487 T:1759507488   ERROR: CCurlFile::Open failed with code 404 for http://mirrors.kodi.tv/addons/isengard/addons.xml.md5
01:38:01  17.783735 T:1759507488   ERROR: Open - failed to open source <http://mirrors.kodi.tv/addons/isengard/addons.xml.md5>
01:38:01  17.783939 T:1759507488   ERROR: Failed to fetch checksum for directory listing http://mirrors.kodi.tv/addons/isengard/addons.xml for repository repository.xbmc.org.```

Kodi mirror appears to be acting up.  Can you connect to that URL with a browser?

I can see the following

b507cfee36e2532308c22af5a37a3b61 addons.xml

I was having the same issue. I can ping other sites from the console, but scrapers and other addons can not connect to the internet. I stream files from a server on my network and they still play just fine. I removed everything in the osmc user home directory and rebooted. That did the trick, so something messed up, probably settings in the ~/.kodi directory.
rm -rf ~/.kodi
shutdown -r now
Above will remove the kodi settings directory. Which will remove all of your sources and settings. kodi will recreate it on reboot and you’ll have to set everything up again, but does allow addons to reconnect to the internet again.
EDIT: moving as a backup would also work if you have the patience to dig through and figure out where kodi is jamming up.
mv ~/.kodi ~/.kodi_backup

Suggest to use mv .kodi .kodi_backup as it will just move the .kodi settings so that you still have it as a backup to recover some of the work and reboot would save the efforts to power cycle after the shutdown