I am testing some routers with that issue .
The cause for that happen is that routers do not allow bruteforce attacks .
This particular router i am testing block wps requests after 3 attemps , then only after 60 Seconds allows more 3 tries , and then after that block wps until next reboot .
Also this particular router does not allow reaver associations .
I am be able until now to go thru with wps requests in reaver by this way :
association with aireplay :
aireplay-ng -1 20 -a xx:xx:xx:xx:xx mon0
and then with this particular command in reaver :
reaver -i mon0 -b xx:xx:xx:xx:xx -c x -A -N -E -vv -d 60
if you recieve a time out even with this delay , then you must increase the delay more .
Instead 60 , use 70 .
i also tested a router that blocked wps with same protections , but this one did not allow your mac address again .
and since you can not make an association with reaver then i need to put down mon0 change the mac address and start everything with aireplay and reaver .
I like these challenges because we happen to learn a lot with new wps protections .
Maybe i will create a thread specifically with some techniques that can be used in wps attacks
the most important thing in the attack is a good signal to the AP , at least -65dbm