replacing airport base station with mesh

Netgear Orbi depending on model uses separate 5ghz radio for backhaul but can also use ethernet.

As long as your ethernet is gigabit standard and was properly installed it is still superior to wireless for backhaul. On paper wireless looks great.. it is only the reality that has a problem. In fact since you have wired outlets I would be thinking carefully of other systems. A lot of the money you spend on mesh is building units that don't need wires. The actual link speed on the RBK50 units for example is only 2 stream, ie 866Mbps. The backhaul is 4 stream, 1733Mbps or some such number. This is done so multiple nodes can achieve full speed rather than using the same wireless for backhaul as connection and lower speed divided between clients.

Gigabit smashes the speed and reliability of this. Plus it will work for ages without jamming up all the spectrum in your house.

If you buy standard routers with WAP mode for example, they will do 3 stream AC or 4 stream AX if you spend big (IMHO Don't buy AX yet.. it is still too early). Or you can buy WAP products designed and built as such.. although finding ones that suit is kind of hard.

It is important to understand a Cheap WAP and even a second hand router will do really well as a WAP when setup correctly. I have used lots of brands like Asus, Netgear, TP-Link, Synology. In fact at the moment I am running a pair of Asus.. you can mix the models.. but I have RT-AC88U downstairs wired to much older AC68U upstairs. The upstairs one I tested in both AiMesh mode with wireless and wired backhaul.. no surprises.. wired won by a mile. And WAP mode where the Asus can be setup as purely Wireless Access Point, as an option it has available in the setup. This works rather better than generic routers that lack true WAP mode. The advantage is access and speed.

I have express setup to join a wireless network. It works no problem.. but I tend to wire things, which is hugely better. Anyway that is up to you. Pick the right equipment that is Apple protocol aware, such as Asus or Synology if you go this way.. Netgear can be problematic. TP-Link some good some bad. The later two do not maintain firmware very well. Whereas Asus and Synology are right on top of issues and post new firmware regularly even for old products.

You can also go Ubiquiti or similar semi-pro systems. I would not recommend it unless you are network savvy or have access to assistance. The learning curve is pretty steep and well just remembering it all can be daunting. I did test it out.. it worked very well but IMHO it is over complicated for home.

FWIW. My previous Apple-based network consisted of a 802.11ac Time Capsule, two 802.11ac AirPort Extreme base stations and a wired RV180 Cisco as my "main" router. All were interconnected by an Ethernet backbone. I started my Ubiquiti journey by replacing both Extremes with UniFi AP-AC-Pro WAPs. In addition, I installed the Ubiquiti Controller on one of my Macs. Think of the controller as similar to the AirPort Utility. I then used the controller to configure the WAPs for my network.

I stayed with this configuration for about 6 months and then replaced my assortment of unmanaged Ethernet switches with UniFi Switch 8 POE-60W managed switches. Again using the controller to configure them. Shortly after I decided to get a UniFi Cloud Key. This allowed me to run the controller from the key freeing up the Mac for that duty. Using the key also allows you to access the controller from any device on your local network ... or remotely if needed.

Finally, I replaced the Cisco with the UniFi Security Gateway (USG), leaving only the Time Capsule from my original network configuration. You can go with a similar upgrade path or choose one of your liking. I went my route basically to become familiar with the Ubiquiti products. Now that I'm comfortable with them, my next network project would be to just start with all Ubiquiti devices from the get go.

I pretty much second the comments provided by LaPastenague. In my case I replaced my Apple-based network with Ubiquiti UniFi devices. Like you, my home is wired for Ethernet. My only regret is I didn't switch earlier. The Ubiquiti gear does take a bit more of a learning curve, but once you do, you'll find it feature-rich and highly adjustable to meet most, if not all, of your networking requirements Overall bandwidth performance is stellar and I have no issues with streaming 4K content to any of my devices in my home.

I noticed that WiFi 6 is coming out. Thoughts on upgrading to that capability?

WiFi 6 is AX I mentioned. No client devices use it.. yet. They will slowly come out over the next few years but just at the moment it is buggy and most products need a lot of refinement. If you like to live on the bleeding edge and pay for the privilege go for it. But good grade AC products which are mature and working well, will give you serviceable life without the hassle. OR COST. Speed gains are much lower than suggested and for most people a properly wired network with AC WAPs will be better than purely wireless AX.

UniFi AP do have a simple phone app to do basic configuration. The problem is you need more to get value out of the system. You need a controller. They also are designed for ceiling mount or wall mount. And you don't get extra ethernet ports you do with a more standard router / WAP.

You can mix the UniFi AP with existing routers. You will turn off the wireless, in the Extreme and for most of your network that makes them dumb switches. Depending on their age it might be worth considering something else though. You only need one router. In the UniFi type system you want a POE switch somewhere to power the units. That switch can replace one Extreme.