Internet stopped working in Ubuntu 20.04?

Question

ubuntu

I recently rented a server with Ubuntu 16.04, upgraded to 18.04, and then to 20.04 and after that I couldn’t connect via ssh, connected through the control panel and after ifconfig realized that the network interface was gone (only lo was shown).
I tried to raise the interface - it worked, but the Internet does not work. I tried to restart networking.service and other services associated with the word network but I get an error

Failed to lower RLIMIT_NOFILE's soft limit to 1k function not implemented

- googling, yandexing and ducking did not make it clear what the problem is and how to solve it (or I'm stupid).

If needed:
Output ifconifg(with interface raised)

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536                                                                            
        inet 127.0.0.1  netmask 255.0.0.0                                                                               
        inet6 ::1  prefixlen 128  scopeid 0x10<host>                                                                    
        loop  txqueuelen 0  (Local Loopback)                                                                            
        RX packets 0  bytes 0 (0.0 B)                                                                                   
        RX errors 0  dropped 0  overruns 0  frame 0                                                                     
        TX packets 0  bytes 0 (0.0 B)                                                                                   
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0                                                      
                                                                                                                        
venet0: flags=211<UP,BROADCAST,POINTOPOINT,RUNNING,NOARP>  mtu 1500                                                     
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 0  (UNSPEC)                                  
        RX packets 7  bytes 316 (316.0 B)                                                                               
        RX errors 0  dropped 0  overruns 0  frame 0                                                                     
        TX packets 0  bytes 0 (0.0 B)                                                                                   
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Conclusionip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN                                                     
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00                                                               
    inet 127.0.0.1/8 scope host lo                                                                                      
    inet6 ::1/128 scope host                                                                                            
       valid_lft forever preferred_lft forever                                                                          
2: venet0: <BROADCAST,POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN                               
    link/void

How to solve it?

Answer 1

try looking at netplan