Hello! I have a question.

I use a video player at client to receive a video stream from server, video player use wlan0 to receive video stream, then I use iptables at middle router to change some packet's IP destination addr, so 1 stream become 2 streams.

1st stream received by wlan0(192.168.1.1) and 2ed stream received by wlan1 (192.168.2.1).

Of course I got a problem, video player seems don't recognize those packets that received by wlan1(video looks not smooth). So,I use iptables change packet incoming interface like this:
Well, it solved problem! The video looks smooth again!

But, why? Why sk_buff->dev (-j ROUTE --iif changes this field) effect application layer? Please help! Thanks~

Wait, so are both interfaces wlan0 and wlan1 on the same machine?

If that is the case video is very sensitive to packets arriving out of order and also with packets no arriving at a constant rate (jitter). So if you are splitting the stream of packets and then letting the application re-assemble them then you are probably cause these issues.

Also, how to you know your application is receive both streams of packets? Could it be receiving only that packets from say wlan0?