Convert wifi signal to wired signal

Question

I have a Rpi which is unable to connect to wifi, but it has Ethernet port. In which mode should I use my Tp-link device to convert my existing wifi to wired signal? I tried out the wifi extender to this task, but in that mode the tp-link device will produced an another wifi signal, which caused problem -> The 2 wifi signal interference caused slowness in speed on both wifi signal.

So the tp-link should only get the wifi signal and forward the signal with Ethernet cable to my Rpi.

1. Wireless Router(Default): In this mode, the device enables multiple users to share the Internet connection via Ethernet port. The LAN devices share the same IP from ISP through Wireless port. While connecting to Internet, the Ethernet port works as a WAN port.
2. WISP: In this mode, the device enables multiple users to share Internet connection from WISP. The LAN port devices share the same IP from WISP through Wireless port. While connecting to WISP, the Wireless port works as a WAN port. The Ethernet port acts as a LAN port.
3. Access Point: In this mode, this device can be connected to a wired network and transform the wired access into wireless that multiple devices can share together, especially for a home, office or hotel where only wired network is available.
4. Range Extender: In this mode, this device can copy and reinforce the existing wireless signal to extend the coverage of the signal, especially for a large space to eliminate signal-blind corners.

Answer 1

There's no option that'll do exactly what you want, although "WISP" mode is fairly close and might work in your case.

However, WISP mode is for connecting to WAN, so it won't bridge both sides – the description says that the Wi-Fi connection will be considered the "WAN port", meaning the TP-Link will still create its own IP subnet, which might be undesirable. (Like "chaining" two routers, you'll have to mess around with static routes, or with port-forwarding.)

Real bridging or "pure signal conversion" is generally impossible with Wi-Fi clients, as the client device isn't allowed to forward other devices' MAC addresses from the Ethernet side; in other words, Wi-Fi isn't symmetric. It could be done if both the Wi-Fi router and the TP-Link client supported the special "WDS bridge" mode, but most home devices don't. It could also be emulated if the TP-Link supported "L2 NAT", but sounds like it doesn't.

There are however some devices sold as "range extenders" which can be switched around to act as a Wi-Fi client (bridge mode), allowing you to connect the RPi to their Ethernet port, and they do implement L2NAT allowing the RPi to be in the same subnet as your main Wi-Fi network.