Changing the channel on the router may just help sort this issue as the bandwidth does have some room for manoverability. The AV sender probably has a far more powerful signal and as it runs on a microwave frequency would be interfering to some extent. If you've got all the boxes (wireless router, AV sender etc) on the same desk/ sideboard, this certainly won't help. Try moving one of them and see if the interference drops off. It may not actually be the signal per se, but rather the boxes interfering with each other