This can happen when you have configured a web/http connection but there is no web server on the device at the port you configured.
- the connectd_installer program DOES NOT install a web server, or VNC server, or any other server that you might wish to use remote.it to connect to.
- by default, there is no web server on port 80 running on a Raspberry Pi.
- If you want to connect to a web server on your Pi, then you will need to install and configure that server for whatever purpose you have in mind.
Another common case is that you are using an application, such as LuCi or node-red, which uses a web connection for its user interface. You may not think of this as a "web server", but underlying the application is an http (web) server.
If you in fact have installed a web server or application on port 80, make sure it is running. In this example I have installed the "nginx" web server but it is not running.
sudo netstat -lpn | grep tcp
pi@raspberrypi:~ $ sudo netstat -lpn | grep tcp
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 401/sshd
tcp 0 0 0.0.0.0:5900 0.0.0.0:* LISTEN 449/vncserver-x11-c
tcp6 0 0 :::22 :::* LISTEN 401/sshd
tcp6 0 0 ::1:3350 :::* LISTEN 457/xrdp-sesman
tcp6 0 0 :::3389 :::* LISTEN 492/xrdp
tcp6 0 0 :::5900 :::* LISTEN 449/vncserver-x11-c
Note that nginx is not displayed and there are no lines which contain either:
tcp 0 0 0.0.0.0:80
tcp6 0 0 :::80
which would indicate the presence of some program listening for TCP traffic on port 80.