Recently I got "error 181" . last one more years I never seen this error and I never changed ( may windows update) system. I got recommendation to resolve this issue from community but it wasn't resolved. Please send me how to resolve this issue.
What I did.
If you have followed all the above steps, but Bitdefender is still unable to connect to the server, there may be an issue with the way the network is configured. To correct it, please flush and reset the DNS by following the instructions below.
Open Command Prompt with administrator privileges: click the Windows Start ⊞ menu, type cmd then right-click the Command Prompt option in the search results and choose Run as administrator.
Type the following at the command prompt:
Type ipconfig /flushdns and then press Enter on the keyboard.
Type ipconfig /release and press Enter.
Type ipconfig /renew and press Enter.
Next, type netsh winsock reset and press Enter
Finally, type netsh int ip reset and press Enter.
Restart your computer afterwards.