Proxmox guest cannot access Internet

[techlists at phpcoderusa.com]

Hi,

Was able to install Proxmox and installed a guest - Ubuntu server 
20.04lts.

Issued : sudo apt update and this is the response:

- - -
Err:1 http://archive.ubuntu.com/ubuntu focal InRelease
   503  Service Unavailable [IP: 185.125.190.36 80]
Err:2 http://archive.ubuntu.com/ubuntu focal-updates InRelease
   503  Service Unavailable [IP: 185.125.190.36 80]
Err:3 http://archive.ubuntu.com/ubuntu focal-backports InRelease
   503  Service Unavailable [IP: 185.125.190.36 80]
Err:4 http://archive.ubuntu.com/ubuntu focal-security InRelease
   503  Service Unavailable [IP: 185.125.190.36 80]
Reading package lists... Done
Building dependency tree
Reading state information... Done
All packages are up to date.
W: Failed to fetch 
http://archive.ubuntu.com/ubuntu/dists/focal/InRelease  503  Service 
Unavailable [IP: 185.125.190.36 80]
W: Failed to fetch 
http://archive.ubuntu.com/ubuntu/dists/focal-updates/InRelease  503  
Service Unavailable [IP: 185.125.190.36 80]
W: Failed to fetch 
http://archive.ubuntu.com/ubuntu/dists/focal-backports/InRelease  503  
Service Unavailable [IP: 185.125.190.36 80]
W: Failed to fetch 
http://archive.ubuntu.com/ubuntu/dists/focal-security/InRelease  503  
Service Unavailable [IP: 185.125.190.36 80]
W: Some index files failed to download. They have been ignored, or old 
ones used instead.
- - -

Same issue as with VirtualBox on Kubuntu 22.04 and Kubuntu 20.04

I do not have this problem when installing VirtualBox on my Win 10 
laptop.

I wonder if it is my router...????

I'll take a look.

Any thoughts on how to troubleshoot is much appreciated.

Thanks!!
Keith