/ip1 is your primary server, /ip2 is the secondary — the client tries ip1 first, and if it can’t connect, automatically fails over to ip2
/connectiontimeout:5 sets how many seconds before it switches (5 seconds is typical)
There’s no /redundancy flag needed on the client side — that’s only for the server startup command
The docs also mention that Runtime → Startup in Designer has a RichClient CmdLine field that auto-generates the correct command line for you based on your redundancy settings. That’s the easiest way to get the exact right syntax — just copy it straight from there rather than hand-typing it. Worth checking if that’s what you tried and it still didn’t work.