hi, maybe you can post some code/bp to take a look what you did.
generally in a multiplayer game you usually want to replicate from server to client, but for a pawn which receives input from a player controller you want to replicate from owning client to the server. another point is to only replicate te stuff you really need as more stuff getting replicated as more network lag will appear, so make sure you filter the cases when and where you need to replicate stuff. only check the reliant flag for stuff which is absolutly important and use the special replication functions to filter in which cases you need to replicate.
the official network tutorials from epic with zak parrish are really good. i needed to watch them several times to understand the background and needed to do some simple examples for each problem/question i had, to learn how to handle it.
hope that helps a bit