whats my best option? get a different modem or a different router?
and thx for answering my query
If it were me ... I'd replace the modem with a modem that had an Ethernet connection.
1) you already have the router and the modem will be able to cnnect to it. That will give you an immediate hardware firewall to protect your LAN (all PCs).
2) The router, with both its wired and wireless capabilities, gives you instant ability to extend your network. All that the PCs require is either a wireless card or a standard network interface card (which it pretty well standard in PCs these days). An extension via USB just cannot be as simple as that!
3) In the comms arena Ethernet vs. USB is a no-brainer. Use USB for what it is good at, e.g. adding peripherals (scanners, cameras, web-cams, hard-drives, etc) easily, use Ethernet for what it is designed for (comms). i.e. don't waste your USB ports on things they weren't designed for.