Turn off the MLO and!!! Oh my god!!! Was that even possible????
in case you didn't know - the BE800 has been on sale since 2022. The BE700 has been on sale since 2024.

I found another problem.
Let me remind you of my network topology: Main BE800v1 → WAN BE700v1-I → Switch → WAN BE700v1-II. All routers and the switch are connected with a Cat7 cable. When creating EasyMesh, both satellites were connected to the LAN port, as described in the instructions; after creation, they were connected via WAN.
After rebooting the main router (for example, after a firmware update), the third router, the one after the switch, BE700-II, appears in the mesh system not via a wired connection, but via WiFi. It won't switch to a wired connection for even half an hour.
To make it appear via a wired connection, you need to reconnect the cable in the switch (either to the same port or a different one) and then reboot the BE700-II. After that, it will hang for a while with an IP address on a different subnet (I have a 10.0.x.x network - the router will be offline for a while with an address of 192.168.x.x), and after that, it will connect via cable, not Wi-Fi.
I haven't tested connecting the satellites via LAN; the BE700 only has one 10 Gbps port and one 2.5 Gbps port - the rest are Gigabit.

This problem only occurs with the router connected via a switch in the EasyMesh system. The BE700-I, which is connected directly to the main router, doesn't have this problem.
Is this a general EasyMesh problem when connected via cable, or is it a problem with the BE800 control unit or the BE700 receiving unit? I don't know.

Satellite IP addresses are reserved manually, not automatically. However, automatically receiving addresses by satellites doesn't change the situation.
Different firmware versions on the BE800 don't affect the situation.
Perhaps the problem lies with the switch, which has suddenly become flaky.

BE700v1 firmware 1.3.2 Build 20260519 rel.14363

BE800v1 firmware be800v1-up-ver1-4-1-P1[20260313-rel47813]pre-release  OR 1.4.1 Build 20260401 rel.14784(4555)

Perhaps this information will be useful to someone

PS. An interesting thought occurred to me. Now, now the revision number is part of the device model name.

Also, MLO won't work in an EasyMesh network with different devices or devices of different revisions. MLO won't work if you have an EasyMesh network consisting of:
BE800 and Be700
BE700 and BE550v1
Be800 and Be550v1

If you want MLO to work in your EasyMesh network with several devices, be sure to buy identical devices and of the same revision!!!

  @Daviii 

You wrote what I already know. MLO does not work in the easymesh network, which consists of different router models. I've even listed the models that have this problem. And how can you produce routers that are "incompatible"? Are we back in the past, 15 years ago?

There is a fact that in the easymesh network, which consists of DIFFERENT models of TP-Link Archer routers (and different revisions of the same models), MLO does not work.

PS

If you turn on the mlo on the be800 and stay near the BE700 satellite, the devices will "hold on" to the mlo from be800, at a poor speed and not switch to satellite. This is the quality of the software of top-end archer routers

  @dustwashere 

I will formulate it more correctly- the MLO network works fine on the BE800, BE700 and BE550v1 devices, but if you connect two different models into an easy mesh network, the MLO will work only on the main device, within its radius of action. Sattelite will not retransmit the MLO network. And you will have to choose either the isi mesh network or the MLO, because if the MLO is turned on, with a weak signal, it will not allow you to switch to a good satellite signal level. And it turns out that there is no full-fledged wifi7 in the easy mesh system of different models of Archer routers. And most likely it won't be, because the BE800 and BE700 have been on sale since mid/late 2023, for three years now. BE550 from spring 2024-2.5 years

It is a pity that tp-link does not report such limited functionality of its top and pre-top level routers.

  @Ethancarters 

1. All devices have the latest firmware version.
2. MLO works perfectly on two Be700s connected in Easy Mesh.
3. MLO works perfectly on Be800s.
4. The "compatibility issue" is "MLO doesn't work in Easy Mesh." MLO also doesn't work in a Be800+Be550V1 network, and it doesn't work in an Easy Mesh network between a Be700 and a Be550V1.
Also, MLO doesn't work in an Easy Mesh network between a Be550V1 and a Be550V2.
This seems like a bit of a "compatibility issue" for a company that produces routers of different models and revisions, claiming they can work in a seamless network with MLO.

So let's call the "compatibility issue" "it doesn't work."

And this is a forum for a company that makes routers. And they can't protect themselves from bots.

So, I've drawn my own conclusions.

  @dustwashere 

Hi,

If a TP-Link product is advertised as supporting "EasyMesh", then this doesn't automatically mean it supports the whole EasyMesh feature set.

To save you from having to read through hundreds of posts is this forum, I'll sum up the TP-Link EasyMesh story for you here.

When TP-Link started out with EasyMesh about 4 years ago, only the so-called "main" wireless network of each of the bands (2.4 GHz, 5 Ghz, 6 GHz) was extended to the "satellite" unit(s) and only via wireless backhaul connection.

Later TP-Link started adding support for EasyMesh via Ethernet backhaul to many of their router models.

More recently TP-Link updated a few router models to support extending the "Guest" and "IoT" wireless networks to the Satellite node(s) via EasyMesh.

TP-Link's most recent addition is support for extending the MLO network via EasyMesh to the satellite node(s). 

However, as far as I am aware is the Archer BE550 V2 currently the sole router that supports this feature already. (someone please correct me in case I am not up to date)

As per Q&A 13 of this article https://www.tp-link.com/en/support/faq/3529/ , both the main router and the satellite nodes need to support this feature in order to make use of it. Therefore, at present only an EasyMesh network consisting of Archer BE550 V2 routers running firmware version 1.3.1 or higher can extend the MLO network to satellite nodes.

Once other router models receive firmware updates that add support for extending the MLO network to the satellite node(s), then this should work even with combinations of those routers.

And yes, the issue of fake posts has been around for a while here.
 

  @woozle 

Thanks for the detailed answer. I've been using this system for 6 or 7 years now. I used keenetic (different models on the mesh network) and asus (also different models).The functionality you have listed as achievements has been working for other manufacturers for a long time (and for some, routers are not a core area at all. And for those who have a profile, this functionality has been considered "ordinary" for five or six years. This confirms the "backwardness" of tp-link software support. But I only found out about it when I started using tp-link products and reading this forum. And I'm shocked.

It wasn't until I bought the tp-link product that I found out that there might be incompatibilities between the models on the mesh network. It was a revelation to me. It's strange to refine the functionality of models that should work out of the box, which have been on sale for three years. I realized that I had made a mistake. I know that I will now buy two different models of wifi7 routers, for example, an asus, and there will be no problem with mesh compatibility and satellite relay. The same problem that Archer be550b1, be700 and be800 routers have (let me remind you, not cheap routers). In any case. I can only wish you good luck in waiting, most likely for a long time. And it's not a fact that successful. 
If you are a user. If the employee is a tp-link, good luck

ps

I'm angry because I feel sorry for the money I spent (let me remind you, about one and a half thousand dollars for routers). When I stop regretting the money I spent, I will only remember that I will not buy tp-link products and will not recommend tp-link products to anyone.

This concludes my interaction with tp-link.