If none of the basic troubleshooting steps work, what more advanced solutions can I try for Steam error 105?

Advanced solutions include: 1) Flushing your DNS cache (using `ipconfig /flushdns` in Command Prompt as administrator). 2) Resetting your Winsock catalog (using `netsh winsock reset` in Command Prompt as administrator). 3) Checking for driver updates for your network adapter. 4) Temporarily disabling your VPN or proxy server if you are using one.