Sounds like a set up issue with router & networking that's causing the issues.

If your brother uses LW, make sure you do not use the same connection or listening ports.

Hard wiring has so many advantages over wireless. Glad to see you chose that option.
However something is astray. Possibly the router's NAT causing issues which is why port forwarding might be more appropriate so the PF rule is directed specifically to your computer (ie: via the ip address.) For some reason UPnp is not working, since Netgear in general have reliable UPnp, however on occasions PF is the better approach; at least more reliable.

I do not know your model of Netgear.

BTW routers will reserve one port per application per computer or/& user account. So that's why it's so important to make sure your other LW's all use different connection & listening ports to any others used on your network. Check via LW's menu bar, Tools -> Options -> Advanced -> Firewalls.
If the ports are the same then change to a port between ports 49152 - 65535. (Any other computer trying to connect via same port will simply be blocked out by the router.)