If you do not see any servers in your browser try the following:
1. Delete your user cache, see here on how to do this.
2. Verify your files, see here on how to do this.
3. In Steam -> Settings -> In Game options there is a dropdown box for "In-Game Server browser: Max Pings/minute. set that to 500 and see if you get servers now, you can try changing this lower or higher as well.
4. Try opening the command prompt as an administrator and running the following commands:
netsh winsock reset
Then reboot your pc and test the server browser again.
5. Disable your windows firewall, open your start menu and type "Windows defender firewall" and open it.
6. Disable your anti virus as a test. we have seen the following AV cause issues with our server browser:
7. Make sure windows is up to date including feature updates which are optional and you need to select manually under windows updates. The latest as of this writing is 1909 for Windows 10.
8. Update your network card drivers.
9. Disable ip flood detection on your router if you have it enabled.
10. MSI motherboards have reported the Killer Lan software suite causes this issue as well, check this article on how to remove it: https://forum-en.msi.com/index.php?topic=178063.0
11. If none of the above has resolved your issues the problem may be outside of your computer or network, a good way to test is to USB tether your smart phone to your computer and test using this connection (a vpn may work as well) If your able to see servers then the issue is with your router or ISP.