Error updating via apt (temporary failure resolving repos)

I am running ubuntu mate 16.04.3. apt-get update can’t access some repos.
Would attempt to update mirrorlist, though I don’t know how its done in apt and not sure its relevant at all.

thcloak@thcloak-mate:~$ sudo apt-get update
[sudo] password for thcloak:
Get:1 http://security.ubuntu.com/ubuntu xenial-security InRelease [102 kB]
Get:2 http://security.ubuntu.com/ubuntu xenial-security/multiverse amd64 Packages [2756 B]
Get:3 http://security.ubuntu.com/ubuntu xenial-security/multiverse i386 Packages [2920 B]
Hit:4 http://ppa.launchpad.net/costales/anoise/ubuntu xenial InRelease
Hit:5 http://ppa.launchpad.net/flexiondotorg/youtube-dl-gui/ubuntu xenial InRelease
Err:6 https://s3-us-west-2.amazonaws.com/brave-apt xenial InRelease
Could not resolve host: s3-us-west-2.amazonaws.com
Hit:7 http://ppa.launchpad.net/ubuntu-mate-dev/welcome/ubuntu xenial InRelease
Hit:8 http://ppa.launchpad.net/webupd8team/tor-browser/ubuntu xenial InRelease
Err:9 http://gr.archive.ubuntu.com/ubuntu xenial InRelease
Temporary failure resolving ‘gr.archive.ubuntu.com
Err:10 http://gr.archive.ubuntu.com/ubuntu xenial-updates InRelease
Temporary failure resolving ‘gr.archive.ubuntu.com
Err:11 http://gr.archive.ubuntu.com/ubuntu xenial-backports InRelease
Temporary failure resolving ‘gr.archive.ubuntu.com
Fetched 108 kB in 2min 0s (896 B/s)
Reading package lists… Done
W: Failed to fetch http://gr.archive.ubuntu.com/ubuntu/dists/xenial/InRelease Temporary failure resolving ‘gr.archive.ubuntu.com
W: Failed to fetch http://gr.archive.ubuntu.com/ubuntu/dists/xenial-updates/InRelease Temporary failure resolving ‘gr.archive.ubuntu.com
W: Failed to fetch http://gr.archive.ubuntu.com/ubuntu/dists/xenial-backports/InRelease Temporary failure resolving ‘gr.archive.ubuntu.com
W: Failed to fetch https://s3-us-west-2.amazonaws.com/brave-apt/dists/xenial/InRelease Could not resolve host: s3-us-west-2.amazonaws.com
W: Some index files failed to download. They have been ignored, or old ones used instead.
thcloak@thcloak-mate:~$

Also, ttf-mscorefonts-installer and flashplugin can’t access the external repos to download the proprietary data (though the packages install normally). I guess it will be fixed along with the first problem.

Ok, trying it a few hours later, apt-get update worked and flashplugin seems to be downloading the proprietary bin normally. Probably a network side issue. Marking it as solved.