Apple Resources - Network Tools

Network Analysis Tools   
Connectivity (Internet)   
WiFi Connectivity   

Creating and Maintaining Home Networks   
Network Quality (Apple)   

HE.NET Network Tools 

DNS - Public DNS service operators!dns-resolvers A public Domain Name Server (DNS) is a name server that may be used in place of, or in addition to, name servers provided by your local Internet Service Provider (ISP). Public name servers offer reliability, security, speed and privacy. Several services now support secure DNS lookup transport services such as DNS over TLS and DNS over HTTPS. TCP and UDP ports used by Apple software products