Change the MTU to 1400 to try.Or change the DNS server to 8.8.8.8.

Have you check the IP address on your laptop?Is the IP address valid? I think the system maybe the problem.

I think it may not work as your 751.Anyway,you can have a try.:D

My router is 841 V8,and it can work with air-play normally.You can use the wireshark and I think you can see the MDNS date.The router will forward the mdns packet normally.

Please tell us your topology.

First,connect your PC to the modem and you can access the Internet. Second,connect your PC to the router,and your router connect to the modem.----ISP---modem----router----PC. Third,do the mac clone...