Resolve coginitive complexity findings in this method.

Options to consider:

• Use list comprehensions to filter the list of yaml files at the begning to non-nested, non-base files
• Use the get_param method to simplify the extraction of the parameter name for subnet. It handles more cases, and will return none if get_param is not used
• Split logic into separate methods (ex: create a method to check each port and return the error message if an error is found)