Checking the firewall settings on the Linux server to ensure necessary ports are open The first step in troubleshooting communication issues between Tableau Server on Linux and external data sources is to check the firewall settings on the Linux server. Ensuring that the necessary ports are open and correctly configured to allow traffic to and from Tableau Server is crucial for successful external communications. Option A is incorrect because reinstalling Tableau Server is an excessive measure before checking network configurations. Option C is incorrect as upgrading network drivers, while potentially beneficial, is not the first step in troubleshooting network communication issues. Option D is incorrect because configuring Tableau Server to bypass the firewall can introduce significant security vulnerabilities and is not a recommended practice.