A firewall applies rules to network traffic according to its configuration and position in the network. It can permit, block or otherwise control certain connections, but a failed request can have many other causes. Home equipment, operating systems and service infrastructure may each apply independent rules, so the relevant layer needs to be identified before changing protections.
A practical example
A computer's application rule can affect one player's connection while a television on the same household network works. That difference suggests a local software policy worth reviewing, rather than proving that every device needs the entire router firewall disabled for streaming.
A common misunderstanding
Do not disable all protections as a routine playback fix. Use documented, narrowly scoped rules for the actual application or connection and retain the original configuration for a controlled comparison.
Related terms
Stable technical definition. Editorial approach