VAST error 301, aka VAST redirect timeout reached, is an error that can be caused when a VAST redirect tag does not return a response within the timeout (5 seconds is the default) specified in a wrapper element. It could include request errors, such as an invalid URI, unreachable or request timeout for a URI, security, or other exceptions related to requesting a VAST URI. It could also be due to a high latency connection (for example, 3G) or simply a slow response from a buyer. To Fix the error, the publisher should Increase the timeout limit of your player via the SDK and the buyer should ensure that the VAST redirect URI is reachable and no protocol issues exist (for example, responses hosted on HTTP and served to an HTTPS site.