It was not possible to connect to the redis server(s); to create a disconnected multiplexer, disable AbortOnConnectFail. SocketFailure on PING
Azure Redis Cache only enables the SSL endpoint by default. The most secure approach is to set "ssl=true" when calling ConnectionMultiplexer.Connect().
Alternatively, you can use the Azure Portal to enable the non-SSL endpoint on your Azure Redis Cache, but then your password and all data will be sent in clear text.
I had exact same exception and it turned out to be corporate firewall, which is blocking port 6379, 6380.
I copied my test console app in an environment outside company network and connection was successful. So if Redis server is running on the internet and your network is behind a firewall make sure the ports are open.