Please follow the below steps to allow SQL express communication in the firewall.
- Open SQL Configuration Manager (You can find such an option from the start button)
 - Expand SQL server network configuration and click on Protocol for SQL Server
 - Enable TCP/IP.
 - Right-click on TCP/IP and go to properties.
 - Add port 1433 in all port text boxes.
 - Restart the SQL server services.
 - Go to windows firewall with advanced security
 - Click on the inbound rule > New Rule > Port > TCP > Specific port (Add port 1433) > Allow connection > Name of the rule and click on save.
 - Click on the outbound rule > New Rule > Port > TCP > Specific port (Add port 1433) > Allow connection > Name of the rule and click on save.
 
If you need any help then you can check Server Migration | Server Management | Server Security (activeservers.in)

