Undo all the stuff you tried before to get it working, and simply enable UPNP. Is your brother forwarding ports to the PS3? If he is tell him to not forward port 80 like the dumb guides say to do. And tell him he shouldn't have to forward any ports anyways, if UPNP is enabled. If you do forward ports, don't forward port 80 to either console.
[CPE] CenturyLink NAT/UPnP Troubleshooting Guide – Zyxel How to Enable or Disable the UPnP feature. To enable/disable the UPnP feature go to menu, Advanced Setup → UPnP. Set the UPnP state, Enable/Disable. Set the UPnP NAT-T state. Select "Apply" to save your changes. If disabling UPnP, reboot the modem/router to close all currently opened UPnP sessions. UPnP not working with Xbox Live NAT type failed!! HELP!!! - PlayStation Nation - GameSpot Make sure UPnP is enabled even if the PS3 says its unavailable Enable it both on PS3 and Router also make sure no one else is using the routers connection. 12 years ago 420Token420 What Is UPnP & How Do I Set it Up in DD-WRT? May 08, 2015
UPnP and NAT-PMP both allow devices and programs that support them to automatically add dynamic port forwards and firewall entries. The most common uses are in gaming systems (XBox, Playstation, etc) and BitTorrent programs like uTorrent, which both rely on allowing inbound connections to a local service.
Jun 21, 2007 networking - How can I forward a port when using PdaNet
UniFi - Enabling UPnP on Ubiquiti Security Gateway
Do You Need to Have the UPnP Enabled on Your PS3? | Our Sep 15, 2017 How To Configure Your Router for Gaming - Page 4 of 8