I run a small coffee shop and want to offer free wifi to my customers while also having a secure network for my point of sale system/internal network. What is the best way to do this on a limited budget? And what is the best way to protect the secure network?

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Just linking a access point or router to your network with a LAN cable will give the customers access to the Internet BUT will also give them access to your local network. (Assuming you have a ADSL Router in place with internet Linked) This is the most inexpensive route.

- A access point is preferred. Connect a LAN cable to the WAN port on it.
- A router will cause IP address conflicts on your network because it also has DHCP. Disable it or connect a LAN cable to the WAN port on if it has on.

A separate ADSL/Internet line is prefigured but more expensive.

Remember to change your password often else people WILL abuse it and bring down your client's speed.

Hope this helps.
Grant