I have the following phenomenon. In my apartment an AVM Wi-Fi router is running in the 2.4 GHz frequency band. The router is pretty central and the signal strength is good to very good in the whole apartment. However, I often have problems in the bedroom, although the Wi-Fi connection is good according to the device with a good signal strength, but e.g. Browser or other apps do not access the internet. This happens with both the smartphone and the notebook. It also happens that it works again from one second to the next and then does not work again just as quickly. The bedroom is not further away or has no special "shielding" like any other room. And as already mentioned, the WLAN connection exists according to the display. I'm also not aware that there are any special sources of interference in this room.
Try to choose another WLAN channel. Possibly. Your neighbor will disturb your network.
Assume that this is normal.
If Wi-Fi has to penetrate through walls or ceilings, it depends on the design of the house on whether it works.
Of course you can try switching to 5 GHz frequency band and see if that works better, but if you have problems with the transmission, the 2.4 GHz is more reliable to my knowledge.
Or you activate both frequencies then the devices can change in an emergency, but sometimes there are problems.
As already mentioned, the WLAN connection is established, only internet communication is not possible.
