Why must my router be used as an access point?

[papaalpha2010]

Kind of lengthy so please bear with me. We have a wireless modem set up which provides wireless internet throughout the house as well as hard lined Ethernet ports in select rooms. The wireless on the far side of the house, which is used as a rental, is really weak so we decided to look into setting up a wireless router on the opposite side of the house that the modem is on to provide the area of the house that is being rented out a more reliable internet connection. The Ethernet port on the wall allows us to access the internet when hard lined into a device by itself. However, when that Ethernet port is plugged into a wireless router, a TP-Link Archer C7 to be specific, anything connected to the router cannot connect to the internet. We have called every tech support line we can use and so far they have said that we have to use it as an access point and not a router. My question is, how come it has to be used as an access point and why can it not be used as a wireless router?

 

[Someone Somewhere]

A router and a wireless access point are two different devices. When produced in one box, they're usually called a 'wireless router' - however, this is still two separate tasks it is performing; connecting wireless devices to a wired network (WAP) and routing layer three traffic between separate layer-2 networks (router).

You need the former, not the latter.

 

[rhysiam]

You can actually still set up that Wireless Router as a "Wireless Router". You just need to configure it properly and you will end up with a separate network in the rental property behind TP Link Router. The problem with doing that is that you end up with double-NAT, which can cause random and hard to diagnose problems for some specific traffic (particularly secure VPNs, for example). Here's a brief run-down on double-NAT: https://kb.netgear.com/30186/What-is-Double-NAT

You're best just using the TP Link as an access point. I do this at home with an Archer C5. You go into the settings of the TP Link unit, turn off DHCP, give it an internal IP address that's on your main network but outside your DHCP range, then let it reboot. Once it's up, just connect the ethernet cable to the LAN (not WAN, LAN!) port on your "access point", and everything should just work. The Archer C7 will continue to function as a basic network switch, so any devices plugged in will have traffic switched appropriately. Any wireless devices will just join your one local network. Just leave the WAN port empty.

*edit* -> I (or plenty of other people here) can give you a more detailed run down of what you need to do if the above paragraph was incomprehensible tech-jargon, by the way. We just can't give you specific instructions without knowing the IP address of your current router and DHCP range.