Hey i have a problem with my ps vita not being able to connect to the psn the router i have is a linksys wrtn120. I'm tired of not being able to use my ps vita to the fullest please help me with my problem thank you.
It's probably a problem with your router configuration, unless your Internet service is something other than cable modem, DSL, or FiOS; in which case it might be an issue with your ISP. Make sure that Universal Plug and Play (uPnP) is enabled on your router. Also the firewall should be configured to allow unlimited outgoing connections.
You have to log in to the web interface of the router using a web browser, and check the router settings. The instructions for doing so are in the manual for the router. Some routers won't allow you to do that wirelessly by default, so you may have to connect to the router using a PC, or other device that can connect to the router with an Ethernet cable.
This problem is so annoying. Ive had an issue with my PS3 and now the Vita. What worked for me is I had to go into my AT&T DSL modem (Motorola 2210-02) change this setting "Let LAN device share Internet Address?" to Yes, use public IP address. The default is No, use private IP address. After that my PS3 was NAT Type 2. I didnt have to do anything on the PS3 side just connect to the internet, but then my Vita was still NAT Type 3. So then I had to set a static IP address on my Vita and go into my Belkin Wireless Router (Belkin F5D7234-4 Wireless-G Router) and put my Vita's IP into DMZ. After that my Vita was NAT Type 2. Not sure if that is the safest way, but absolutely nothing else was working for me.
A host in the DMZ will never be NAT 3, unless there is another firewall in the network somewhere; so that does work. You always want to get a public IP address from the modem, but the address needs to be assigned to your router. Your router will assign private IP addresses to each host on the LAN, including both consoles; but that won't cause you to go to NAT 3 by itself. Did you enable uPnP?