A secure connection in the M1 Touch Pro app is done using the secure port (2601) from the M1XEP (Ethernet Module).
It is highly recommended that you use a username and password in your M1XEP when using the secure port. This username and password is then used in the app to make a secure connection to your panel.
Without using a username and password makes your connection weak, and when using the panel over the internet will make your connection available for anyone to connect to it providing they know the IP and port to your panel. This makes your panel not secure.
If you are not wanting to use a username and password when using the secure port, then you may want to use the non-secure port (2101). This will make the app connect a lot quicker and will also send commands a lot quicker. Connecting to your panel with the secure port without a username and password is pretty much the same as connecting with the non-secure port.
It is not recommended to use the non-secure port when connecting over the internet. The non-secure port is recommended when connecting on the local WiFi without going over the internet.
It is not recommended to use the secure port without a username and password when connecting to the panel over the internet (or even on a local connection).
Using the secure port with a username and password is highly recommended when connecting over the internet.