Hi, in need of recommendation for current house WIFI setting.

Unifi package: 100mbps
Devices:
Modem: Alcatel 1-240G-P (since 2012)
Router: D-Link DIR-842 C2 (since 2018 as previously used another D-Link router for older package before changed to this package)



Problems:
1. Once or Twice a day, the WIFI speed will dropped from 100mbps to 45/50 mbps and need to restart both modem/router to get back the optimum speed.
2. Stayed in double storey, modem+router located at ground floor. Hence, the speed will drop further by 50% or more for upstairs rooms. I think this is for sure due to the distance and walls that further interfere with the quality of the WIFI.

Was recommended to fix the dead zone area or boost the WIFI signal (problem statement no.2 above) using mesh device. From Unifi add-on package, there was this device TP-Link Deco M4. For a double storey house with about 1.8k built up space, is it recommended to get this device Deco M4 or alternative?

Also, is it better to get it from shop/online vs TM?

Thanks a lot

Ok thanks a lot for shared info and link.

So, setting it up, using existing router and connect 1st Deco unit wired next to it, and then position the other Deco unit to upstairs - somewhere center in between the rooms and main unit?

With this setup, do I need to provide the username/password of my current Unifi account?

Ok got it. Thanks a lot. Just purchase it, awaiting the item.

Hello,

Setup and done default configuration in which both TP-Link M4 is currently set as AP for both.

The first AP is just 30cm away connected to existing D-Link router wired. The second AP is upstairs center small hall.

Initial review after 2 days:
1. Ground floor
- By making sure the initial router speed is at the most optimum (restarted first and get 100 Mbps in average download speed - my current package), I manage to get this speed the same from the ground floor connected to 1 of the AP device. However, after a while, I think around 10 mins plus (not so sure), then the speed drop and further check on Speedtest confirm connection dropped to be around 10 Mbps for download speed.
- Since the original router is still running, connect it and check using Speedtest, confirm the speed it is still 100 Mbps. Then, decided to change back the wifi connected to the 1 from TP Link, the connection went back to 100Mbps.  . So, it can't get to maintain the same with TP M4 link mesh on ground floor.
- And then, if I went down again from master bedroom, upon reaching AP 1 at the ground floor, i get back the 10 Mbps again. Try to reconnect to old wifi, confim the speed is 100Mbps download speed.
2. Upstairs
- By making sure the initial router speed is at the most optimum (restarted first and get 100 Mbps in average download speed - my current package), I manage to get about 30Mmps of the speed consistently. Still I remember last night I can get higher (about 50 Mbps). Still, for upstairs, it is much better overall in my master bedroom. Still, due to the position, AP 1 next to router is just exactly below of my laptop on my master bedroom. 90 degree. But, at upstairs hall area where the AP 2 is present, not sure which AP did the laptop is connecting.
So, some advice?

This are the settings I see it is listed in the Deco app:
IPv4 is Dynamic IP
IPv6 is disabled
Operation Mode is Router (which is weird, currently is setup as AP, but I didnt bother to change this, as wifi is working just the speed weird, this can be issue?)

Also, there is a new update from the Deco app, for the new version: 1.4.3 Build 20200918 Rel. 74289. Should I update it since i see some bad review on this? So far my Zoom online session no issue as shared by certain group of people in TP-Link forum for M4.

Firmware build number? How to check? I cant find anywhere. However, under Update Deco, it detected both my AP is Deco M4R and stated there is a new firmware version to be updated. Ignore? Also, now I recall, when setting up, first AP I can choose M4 model but second AP, there is no M4 except M4R from the Deco app. Normal?

How to turn off the wifi? I cant off the router right as now the first main AP is connecting to the router. So, have to make the AP main as router?

Ok. Deco version: 1.4.2 Build 20200727 Rel. 37987

Ok, will set it up as router. Do i need to reset both AP set before restarting? Just go to the Deco app and remove both and then add again?

Ok, recommended to update the firmware?

Till now, the devices is still not smart enough to change AP. 

Ah ok. So, for example, main WIFI network set to 5Ghz, and create a separate Guest network that used 2.4Ghz - both using diff SSID.

As for firmware, so if I only have Google Android devices, recommended not to update?