Asterisk can't connect to zoiper

Hello.

I'm not an expert on Asterisk, but "408 Request Timeout" is an error that usually occurs when the request reaches the server but then some kind of problem occurs that prevents the server from processing the request, or when the client takes too long to send the request. Therefore, I think this may also occur if the Lightsail instance has low specs and is unable to process the data.

I think the port number you listed can also be used with Lightsail.
https://docs.aws.amazon.com/lightsail/latest/userguide/understanding-firewall-and-port-mappings-in-amazon-lightsail.html#specifying-ports

The ports that you can specify in a firewall rule can range from 0 to 65535. When you create a firewall rule to enable a client to establish a connection with your instance, you specify the protocol that will be used (covered earlier in this guide), and the port numbers through which the connection can be established. You can also specify the IP addresses that are allowed to establish a using the protocol and port; this is covered in the next section of this guide.