Question about TP-Link Re450

I can't say anything about it, I only have one such repeater and it works fine.

Repeater to repeater is a poor solution at best. Each repeater is a separate WiFi device with its own name. For example, your router has two bands, 5 GHz and 2.5 GHz, which you name OTTI5 and OTTI2. The first repeater also has two bands, but must use different names, e.g. OTTI5A and OTTI2A, and the second repeater also, OTTI5B and OTTI2B. For each of these -- 6 cases in total, you must set a password. Then on your mobile or laptop, you have to connect all 6 volumes once and save the passwords. As you walk around the house, your mobile then switches from device to device, depending on the signal strength. Each switch causes a delay. In addition, there is a real headache when it comes to which device acts as a DHCP server to distribute the IP addresses on the mobile and laptop. If it's just the router, good luck -- what happens if your mobile is switched on far away from the router? But if each device is used as a DHCP server, then a certain IP address range must be reserved for each. Changing IP addresses is problematic.

What you need costs a little more, but is worth the money, namely a "mesh" WiFi. The devices look similar to a repeater. Only, a group of such devices communicate among themselves to invisibly transfer a mobile or laptop from one to another quite transperantly. There are only the two volumes from the router and their two passwords (which can be the same). The mesh devices take these from the router. You only need to store these two in the mobile or laptop. The mesh devices route the IP packets among themselves to and from your router, your mobile only has the one IP address distributed by the router. It works similar to the internet itself, regarding routing of packets.

I use three Netgear mesh devices that plug directly into the wall and I am very satisfied.
They are old models that are no longer on sale, but similar to Netgear EAX15 WiFi 6 Mesh Extender.