Hm, sounds like compiler-related problems, because I myself have no problems interconnecting 32-bit x86 and 64-bit x64 builds, see:



Even i did noticed no problems at interconnecting 32-bit ARM builds (Delphi Client-Side on Android), 32-bit x86 (Delphi Client-Side on Windows) and 64-bit x64 builds (FPC Server-Side on Linux and Delphi Client-Side on Windows) in a commerical project, which's using RNL.

So which exactly for compiler version you are using, and exact which compiler parameters? At FPC you should disable the higher code optimizations, because FPC have often code optimizer bugs, so please test with "-O- -O1" as compiler parameters for to force the lowest code optimization level. And could you give me a example project with sources and binaries, so that I can investigate the problem in a better way?