Q: If a neighbors network shows up on my WiFi list under About This Mac, should I be concerned about security?

In the System Report, is the My Next Door Neighbor network listed under Current Network Information or Other Local Wi-Fi Networks?

Current should be the network you're on, and that should be your own. If My Next Door Neighbor is under Other, that's OK. It means it's available but you're not connected to it. On my Mac, the Other category is all of my neighbors, about 10 of them. Other is like all of the non-selected networks under the Airport icon in the menu bar, they are of no concern because you're not connected to them. They are like the list of radio stations on your radio, they are listed because you are in range of them but they cannot affect you. Unless you're connected.

Duane pointed out that WiFi Explorer (US$15 with three-day free trial) can show you the distribution and competition of surrounding Networks:

From the diagram, you can see the spectrum overlap of two Networks on Channel 1 (Red and Green) and two other networks around channel 5 and 6 (orange and blue).

it illustrates how few clear channels may be available at 802.11b/g/n speeds many Routers try to use in the 2.4GHz band.

In the 5GHz band, a neighbor's network at channel 155 is way too low a signal to be useable by you.

Re: 5G wifi linkspeed is slow (11Mbps)

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There is also a free version of NetSpot

It's more and more common to see many different WiFi networks from neighbors, particularly in apartments and hotels.

Don't worry about them, but make sure you put a good password on your's !

Most of the currently sold wifi routers monitor other networks and which channels they are using (including your wireless phones), and if there is much interference, they will usually automatically choose a different channel.  (In the older routers, you sometimes had to manually choose  a different channel).

Don't worry about them

Oh, they won't get on your Network if you have a good password. But that is not the only problem. If you look at Duane's Network Neighborhood, it is typical of many. The 2.4GHz band is JAMMED with cheap Routers, all trying to shout over each other. and instead of the expected taking of ONE Channel per network, they take a third of the total bandwidth each! There are SIX Routers fighting over that 2.4GHz bandwidth!

Users often complain that their Wi-Fi connection "drops out". That is because there is no way to get a (data) word in edgewise!

If you live in a crowded area, you are just going to have to get a Router with dual-band, including 5MHz band, or you will not be able to get through the crowded mess that is the 2.4GHz band today.

I agree.

That's a good reason to buy Apple's Airport routers!

They are dual banded and automatically hop to channels that aren't busy.

I'm not a network engineer, but I do know that crowded WiFi channels are a real problem and 10 years ago, I would be manually changing channels on my 3rd party routers from time to time, like you are suggesting.   One really shouldn't have to log into their router, though, which is why I like using the Apple routers and monitoring it with the Airport Utility.

I have used Netgear and Linksys routers with similar smart technology, but in my experience, they did not work as well as my Airport Extreme.

I recommend updating routers every 2-3 years, because the technology improves and Apple devices have always been able to take advantage of that new technology.  The Airport Extreme, in fact, is truly superior for larger houses or offices, particularly with basement or upstairs rooms. 

@ut2jimbo:  That is really good information - Thanks !

I believe the Airport Extreme is a pretty good router and it works well in my house (two stories and irregularly shaped).

I will warn you that in my personal experience, my Airport Extreme routers don't last very long.   I have replaced my Airport Extreme 3 times since the first came out.   But, after I gave them my network name and password, all my devices recognized the new router.   The Time Machine backup disk on all of them failed very early.  The first one lasted about 9 months and Apple replaced it without questions.  The second one lasted 3 months.  Apple replaced it.   The 3rd one lasted two weeks, so I just gave up using Time Machine, but the router continues to work flawlessly.

Since so many things rely on a wifi connection, I also put my cable modem and my Airport Extreme on a small battery backup ($40).  They don't require much power and it's really helpful if the don't go down during a brief power glitch.

With non-Apple routers, you usually have to go through an annoying sequences of turning each device back on, in order, after a power outage, because they will get their IP addresses mixed-up when the power up.  That never happens with the Apple routers.  I don't know the details, I just know that I got very tired of re-setting all the network devices and computers in the house and nobody in my family was willing to learn that process!

This article shows how to add more Network Access points if you have a large area to cover, or if your house (like mine) is solid masonry construction or wire lath plaster, all of which swallow up the Wi-Fi signal. almost any Router that has 80211n can be incorporated.

Wi-Fi base stations: Extending the range of your wireless network by adding additional Wi-Fi base stations - Apple Suppo…

I suggest you not take the illustrated Wi-Fi to Wi-Fi connections seriously, but instead pull an Ethernet cable to each router location. WiFi-to-WiFi kills more than half your potential bandwidth just forwarding packets. Use Ethernet for the connections between Routers.

what model TP-Link are you using?

(is electrical cable as good as an ethernet cable?)

category-5 Ethernet cables with all conductors present can run up to 1000 Megabits/sec

TP-Link backbone across your house wiring claims 500 Megabits/sec (not too shabby and you did not have to pull any cables). so that is pretty good for your wired connections.

Almost nobody has a connection to the Internet that fast, so extra speed is only helpful for local transfers.

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The TP-Link remote devices you have use only the 2.4GHz band. So if your Wi-Fi connections are suffering from neighbor's interference, you don't have access to the wide-open 5GHz band.

I think as long as the data rates stay good, and do not start to drop off, you could just keep using TP-link stuff.

If you read closely, that Apple document talks about extending an Apple Network with an additional Apple Router used as an Access point, and connected by Ethernet cable. But almost ANY Router can be added to an existing network in this way, to do roaming without having to replace, only extend your existing Network.