Sometimes, when you want to send your Tradingview alerts to MT5, after setting up your MT5 Tradingviewtobot, you may face an unknown error 1001. Error 1001 is an internal MQL WebRequest error which means 1001 - SOCKET_HTTP_NO_CONNECTION.
It is a known issue MT5 but there is no sufficient documentation by the MT5 team. For some reason, your server refuses the connection, the Tradingviewtobot keeps sending a retry request every 2 seconds until a successful connection is achieved. So leaving the EA installed and the MT5 instance open for a few minutes will fix this error.