Once you’ve drilled down into Envoy responses and discovered Envoy generating local responses with the message “Sending local reply with details route_not_found” the next question is _why_?

Often you can look at your route configuration and the headers sent, and see what is missing. One often overlooked problem is host:port matching. If your route configuration matches the domain www.host.com but the client is sending requests to www.host.com:443, it will not match.

If this is the problem you are encountering you can solve it one of two ways. First by changing your configuration to match host:port pairs, going from

domains:
- "www.host.com"


to

domains:
- "www.host.com"
- "www.host.com:80"
- "www.host.com:443"


The other is to strip ports entirely using stripping port from host header. Not that this will only stip port 80 from insecure requests and 443 from secure request. It does not just stop ports when routes are matched, but changes the host sent downstream to also not include the port.