Be sure that you are connected with GoodAccess app.
Go to Settings and Continue with (Security rules) Rules -> Add IP address.
You can use "Autofill" (in case that you are connected to GoodAccess GW) or write GW IP and "Add".
Preview and enforce now.
Confirm your new security rule with "Enforce now"
Congratulations! From now on your system will be protected and accessible only by your team through the GoodAccess network.