The dhcp server provides the ip to the clients but the internet can not be accessed

I'm new to the linux world and I wanted to make a dhcp server with ubuntu, everything turns out well, it establishes the IP address for all the clients, however at the moment of wanting to enter the internet it denies me access, it is worth noting that my server is in a virtual machine.

Here is my server code:

This is the code of the IP address of the computer itself

and this is the error shown