The Deco 9 should be compatible and expandable with any Deco product. This means that a single unit of a Deco product can also be purchased and integrated.

Yes, it should work. According to tp-link website all Decos work together

The Deco systems can be expanded with any other model, i.e. it may make sense to combine a set of 2 Deco M4s or even E4s with the system and thus perhaps achieve even better coverage with more units. A single P9 should cost about the same as a set of 2 M4s or 3 E4s. Some of the individual devices cost almost more than a set of 2.

A restart of the main router will probably help. Otherwise, the P9 can be reset and reconfigured.

I also experienced the same but for only 1 unit. It goes offline and can't connect with the power line or wifi, this happens randomly .

Yes, that is possible, but it is more optimal to use the Deco simply as a mesh system. The two LAN connections are Gbit and you can connect everything to them without having to change the mode. A switch, a PC, the Internet service provider router. Wow, the price for a P9 set is really good. Brilliantly good, even.

Unfortunately, there is no manual. I only found these two links with FAQ's: https://www.tp-link.com/ch/support/faq/2401/ https://www.tp-link.com/ch/support/faq/1464/

It depends on your setup. P9 supports the bridge mode according to the instructions. However, a wired connection is necessary for the main unit, a pure repeater function is not supported. See https://www.tp-link.com/us/support/faq/1432/ This means you can switch off the WLAN from the Archer, attach a Deco P9 unit and output the WLAN there via Bridge Mode (pure WLAN access point). You then place the second Deco P9 somewhere where it still has a good connection to the main unit. Depending on your needs for the WLAN, this setup can also be achieved with other products (e.g. Ubiquiti). If you are looking for a pure WLAN repeater, i.e. you want to keep your WLAN on the Archer and simply boost the signal in one place, you need to look for a repeater, the Deco P9 cannot do this.

Yes, it is compatible. Each P9 router has two 1 Gbit/s ports.

It’s a 2 pin plug so works with both

I can't answer whether it works with UPC, I have a Fritzbox. It works there. However, I have several walls and two floors to "overcome". You can't get there with the specified range of 400m2. I had to install 4 decos, but now it works fine.

Hello Cwalwal, Yep, all three can be connected with an Ethernet cable. Can only recommend the product! Greetings

Well, I've already noticed that it's never worth buying a set of 2. You can get a set of 3 for a little more, or vice versa, you can even get a set of 3 for less (like the Deco M5). However, I don't think that the prices for a set of 2 would be lowered because of that. Therefore, I would always go for the 3-piece set, because you get more for almost the same or less and you can quickly expand at home if necessary because you already have a third device and if two are enough, you already have a spare part at home if something should break :).