Great Partick,
Let's start with the same setup (like the default) and tell each other what you experience, like too much understeer in T1, too much oversteer in T5 and what you tried to change that. What did help and what not. If we have exchanged these a couple of times, we will have a decent base setup and then we can find a timeframe to test together for further tweaks.
Do you prefer a car for this? So far I have tried the 911, R8 and 488. All cars that have some sudden nasty behaviour with my fastest setup.