“Default Gateway Is Not Available” annoying Error

[LNick]

Hi, I have a very annoying problem with the internet connection on my laptop. 

For about 2 or 3 months, "connection drops" (on wifi) have been occurring on my Hp pc (with Windows 10).

When the connection fails, the computer is still connected to the modem but DNS errors appear on the browser. The problem seems to be only on my pc because during disconnections on other devices connected to the same network, the Internet works. In the beginning these disconnections were quite frequent and the connection was re-established by disconnecting and reconnecting me to the modem. Or opening the troubleshooting on Windows I found the problems "DHCP is not enabled for Wifi - Solved" (but I had enabled it from the settings). After a while the problem turns out to be "Default Gateway Unavailable - Solved". The connection is re-established but unfortunately after a short time the problem recurred.

Currently the problem occurs randomly, at least two or three times a day. By disconnecting and reconnecting, the problem is solved but it could also appear even after a short time... 

I've tried a lot of possible solutions but none worked permanently, for example:

- I disabled the energy saving of the network card,

- I uninstalled and updated the "Realtek RTL8821CE 802.11ac PCIe Adapter" network driver from Device Manager.

- I updated Windows 10 to the latest version.

- I ran the commands from cmd:   netsh winsock reset      netsh int ip reset   ecc.

- I reset the network from "Settings".

- I tried to change the wifi channels (between 1, 6 and 11)
- I changed the type of password security
- I tried to install an older driver

- and other possible solutions...

I am quite desperate, I have already written in two Italian forums and this community is probably the last hope ...

I sincerely hope you can help me solve this bad problem.