it rather depends on what was making the connection and was it initiated by you, etc.
Port 443 is a virtual port that computers use to divert network traffic. ... HTTPS is secure and is on port 443, while HTTP is unsecured and available on port 80. Information that travels on the port 443 is encrypted using Secure Sockets Layer (SSL) or its new version, Transport Layer Security (TLS) and hence safer.
Whilst the use of that port isn't a given to be malicious, it rather depends how it is being used (legitimate).
The IP address relates to cloudflare.com but they handle traffic for many services.
Hence details would help.
You could attach a screenshot of the avast alert windows (including the more details option open) if it happens again.
