Hi @rcrepar
Try using the laptop's WiFi as close as possible to your home network router i.e. <20cm and check if it connects and maintains a stable connection.
If it does it may be an antenna problem e.g. loose antenna connection to the WLAN card in the laptop.
Here's the [https://download.lenovo.com/pccbbs/mobiles_pdf/e14_r14_e15_s3gen2_hmm_en.pdf|hardware maintenance manual] for the laptop.
Go to p.73 to view the procedure to remove/replace the WLAN card. This will allow you to check if the two antennas are securely connected to the card.