There are numerous possible reasons for this — too many for me to guess — but I would double-check your networking config for Vagrant is correctly configured and your default route and gateways are correct in the container. Assuming your parent host (e.g. laptop) has connectivity, see if you can ping the parent host IP inside the container, or a known external IP that will respond to ICMP (like Google’s DNS server at 8.8.8.8).

It’s most likely a misconfiguration, followed by a firewall issue. It may also simply be your network stack has become corrupt on the host, in which case a simple restart of the laptop might fix it.

Failing that, I’d start again with a fresh Vagrant configuration file taken from the article and try building and running the container again.

Good luck!