Port forward works with static IP but not dynamic?

[_eternal]

From what I've read, port forwarding doesn't require a static IP from the ISP, right? You just need your router to assign your computer a static LAN IP?

My port forwards used to work when I had a static IP, but I switched to dynamic and now they've stopped. Nothing about my setup has changed so it isn't a firewall issue. My router is the ASUS RT-AC66U; my network adapter is set to use a static IP and the router has reserved my local IP. I've checked canyouseeme for the ports of various programs that are always running (torrent clients, skype) and they all fail.

Any ideas?

 

[azazel1024]

Are you getting a static IP from your ISP? Or did they change it so that you are getting a dynamic IP? If the later you'll need to signup for a dynamic DNS service and have your router support DDNS also.

 

[JackMDS]

Please describe the exact circumstances that the port forwarding does not work.

Did you change your Router's WAN setting from Static IP to DHCP. If Not do it.

Otherwise, under normal ISP service the type of External IP should Not affect Port forwarding if it is configured correctly.

DDNS is needed only to know where to Go if you try connect remotely from another location to a computer with Dynamic ISP's IP.

 

[_eternal]

Thanks for the replies. I figured it out, so in case anyone stumbles onto this from google:

The problem was with the modem. My ISP (Rogers) has a modem that doubles as a router. The wireless part was turned off so that I could use my own router, but there was another option in the modem settings to turn off UPnP and something about a residential Gateway. It worked when I turned both off.

And yep, I might use DDNS, though I think my ISP doesn't change my IP too frequently.

 

[alkemyst]

Good you solved this.

For anyone using a 'real' device like a Cisco ISR router/switch; if you are doing dynamic and static NAT, you have to set up an access list to not go dynamic so your static fires off like this:

ip nat inside source list NAT-DYNAMIC interface GigabitEthernet0 overload
ip nat inside source static tcp 192.168.1.240 8081 58.205.72.214 8081 extendable
ip nat inside source static udp 192.168.1.240 8081 58.205.72.214 8081 extendable
ip nat inside source static tcp 192.168.1.241 8082 58.205.72.214 8082 extendable
ip nat inside source static udp 192.168.1.241 8082 58.205.72.214 8082 extendable
ip nat inside source static tcp 192.168.1.242 8083 58.205.72.214 8083 extendable
ip nat inside source static udp 192.168.1.242 8083 58.205.72.214 8083 extendable
!
ip access-list extended NAT-DYNAMIC
deny tcp host 192.168.1.240 eq 8081 any
deny udp host 192.168.1.240 eq 8081 any
deny tcp host 192.168.1.241 eq 8081 any
deny udp host 192.168.1.241 eq 8081 any
deny tcp host 192.168.1.242 eq 8081 any
deny udp host 192.168.1.242 eq 8081 any
permit ip any any

Also another thing consumer routers/switches let you do is hit your outside IP addresses on the inside You can't do this with a Cisco 'real' IOS device and most like Juniper either.