networking – apt-get update failes after configuring OpenVpn

I have been installing and configuring the OpenVpn server with the help of this video on Hak5.

After configuring all the necessary configurations for both the server and the client, I restarted my VM and tried apt-get update so I could install some other packages to transfer the client keys.

Failure:

Err: 1 http://download.opensuse.org/repositories/isv:/ownCloud:/desktop/Ubuntu_18.04 InRelease

Could not resolve & # 39; download.opensuse.org & # 39;

Err: 2 http://ftp-stud.hs-esslingen.de/ubuntu bionic InRelease
Could not resolve & # 39; ftp-stud.hs-esslingen.de & # 39;

Err: 3 http://ftp-stud.hs-esslingen.de/ubuntu bionic-updates InRelease
Could not resolve & # 39; ftp-stud.hs-esslingen.de & # 39;

Err: 4 http://ftp-stud.hs-esslingen.de/ubuntu bionic-backports InRelease
Could not resolve & # 39; ftp-stud.hs-esslingen.de & # 39;

Err: 5 http://ftp-stud.hs-esslingen.de/ubuntu bionic-security InRelease
Could not resolve & # 39; ftp-stud.hs-esslingen.de & # 39;

Reading the lists of packages ... Done

W: Error getting http://ftp-stud.hs-esslingen.de/ubuntu/dists/bionic/InRelease Could not resolve & # 39; ftp-stud.hs-esslingen.de & # 39;

W: Error getting http://ftp-stud.hs-esslingen.de/ubuntu/dists/bionic-updates/InRelease Could not resolve & # 39; ftp-stud.hs-esslingen.de & # 39;

W: Error getting http://ftp-stud.hs-esslingen.de/ubuntu/dists/bionic-backports/InRelease Could not resolve & # 39; ftp-stud.hs-esslingen.de & # 39;

W: Could not get http://ftp-stud.hs-esslingen.de/ubuntu/dists/bionic-security/InRelease Could not resolve & # 39; ftp-stud.hs-esslingen.de & # 39;

W: Could not get http://download.opensuse.org/repositories/isv:/ownCloud:/desktop/Ubuntu_18.04/InRelease Could not resolve & # 39; download.opensuse.org & # 39;

W: some index files could not be downloaded. They have been ignored, or old ones used instead.

The error may not even be of the configurations that OpenVpn needed to run. I have no idea.

The commands related to the network introduced during the configuration:

$ echo 1> / proc / sys / net / ipv4 / ip_forward

$ nano /etc/sysctl.conf | edited here net.ipv4.ip_forward = 0> 1

$ ufw allows 1194 / udp | the port of the Vpn server

$ nano / etc / default / ufw | The exit and shipping policy changed

$ nano /etc/ufw/before.rules | the following rules added:

* nat

: POSTROUTING ACCEPT [0.0]

-A POSTROUTING -s 10.8.0.0 -or ens33 MASQUERADE

COMMIT

$ ufw enable