Cisco 1800 - NAT Netflix Slow Connection

[Dominic W]

Hi,

Yesterday I set up my Cisco 1800 router to work eventually as the main router facing my ISP's cable modem.
What I've done is basically the configuration below, but although NAT is working, my Netflix connection (using Apple TV) times out.Since I am at work right now I will enter the commands out of my head, hoping someone is able to recognize where the problem could be.
The menu of the Netflix app does work, however, when I eventually want to play a movie it times out.

conf t
 int fa0 <- (Connected to cable modem)
  ip add 192.168.178.180 255.255.255.0
  no shut
  ip nat outside

 int fa1
  switchport access vlan 50
  description Link to Apple TV

 int vlan 50
  ip add 192.168.50.254 255.255.255.0
  ip nat inside

ip access-list ex 100
 remark NAT ACL
 permit ip 192.168.50.0 0.0.0.255 any

ip route 0.0.0.0 0.0.0.0 192.168.178.1

ip nat inside source list 100 int fa0 overload

NAT translations do work and the Apple TV has internet connectivity.
But when playing a movie the Netflix app reports the movie is not available.

Note that I am still using NAT on my cable modem at this modem, so my 1800 is performing NAT and my cable modem is performing NAT.
But I cannot find a reason why it is causing this behavior.

Because of the few amount packets being transmitted I started a 'debug ip packet'.
What I found was that seemingly random packets failed to encapsulate, while others with the same source and destination were just being transmitted.

Anyone has any ideas?

[Mark Malone]

Hi

your config is ok as NAT is working and that's all you need to get it going if not specifying static nats  , the fact your double natting may be causing an issue have you tried as at test to disable the modem NAT and just let the 1800 do it and see if it works ok , just put the modem into bridge mode and pull the public ip address back to the 1800 and leave the modem as transparent to the traffic