Hi @agdian ,
Try [https://www.digitalcitizen.life/how-reset-all-your-windows-10-network-adapters-just-6-clicks|resetting] your network adapters.
With the WiFi connection getting lost problem, try using the laptop as close as possible to your WiFi router and check if there is a network signal available, that you can connect to it and that it stays connected.
If so it may be that there is an antenna connection problem on the WLAN card in the laptop.
Here’s the [https://topics-cdn.dell.com/pdf/g-series-15-3590-laptop_service-manual_en-us.pdf|service manual] for the laptop. Go to p.36 to view the necessary pre-requisite steps and then the procedure to remove/replace the WLAN card. This will allow you to check the antenna connections.