WLAN doesn't work, but only on the laptop and in one room?

Hello:-) I have the problem that I haven't had Wi-Fi in my bedroom for a few days, but only on my laptop. Then I don't even see networks and if so, then only with a very weak deflection. Everything works on the mobile phone. As soon as I go to another room with the laptop, the Wi-Fi works there. I've had the problem since I had a new fan installed in my laptop, but what happened when I suddenly got this strange problem? I also have the current driver on the laptop so it can't be because of that.

But that's really strange… But otherwise does the Wi-Fi work for all devices in the room?

Strangely, yes.

Perhaps the receiver in the computer is damaged and can therefore only recognize the Wi-Fi if it is in the immediate vicinity… I can't explain it any other way… Can't you ask the same people who changed the fan again? Maybe they can help you with that

I just checked again on the PS4, where I connected a LAN cable, but when I switch to WLAN it doesn't work there either. So it's the same on the laptop and the PS4, but not on the cell phone

I suspect that they made a mistake with the filigree cables when taking them apart and screwing them together. Bring that back there and ask them to fix it.

There are providers who make it possible to use mobile data during a wireless connection. Maybe that's the way it is for you and the bad connection is compensated for with your mobile data. You can check your data usage on your cell phone

However, he has the same problem with his playstation when it runs over Wi-Fi…

However, Wi-Fi is no longer displayed on the PS4

The WLAN antennas (for 2.4 GHz and 5 GHz) are built into the laptop lid. These WLAN antennas are routed to the WLAN module with thin antenna cables / coaxial cables (on / through the hinge).
These coaxial cables are plugged into the WLAN module (with an IPEX connector). If you take a laptop apart, one of the IPEX plugs could have come off unconsciously. Or the workshop even forgot to plug the IPEX connector back on.
As a result, the laptop has very poor reception. Maybe even only at 2.4 GHz, but the 5 GHz WLAN (actually has less range) still works at close range (typically WLAN with 2.4 GHz extends twice as far compared to 5 GHz WLAN).

Let the workshop check again whether the IPEX plugs are properly seated. In rare cases, frequent opening and closing of the laptop lid can cause a cable break in these coaxial cables over the years. Then also has bad reception!

PS:

This is what the WLAN antenna with IPEX connector looks like: https://www.reichelt.de/wlan-antenne-mhf-u-fl-lp-068-delock-89457-p179808.html

PPS:

Maybe a WLAN repeater failed or crashed?