I also started to mull over all the code fragments that are lying around to see if I could find a single program for which there is both server and client code. Ao far the only example I have found is on GitHub. The programs on Nordic all seem a bit broken, or have the other half missing.
I found the S130 softmachine and started reading about it. It purports to handle both server and client traffic at the same time.
I also made my first server (central) program using the s120 softmachine but it won’t load directly from the Keil IDE. I tried loading it from nRFGo and it loads, but doesn’t seem to run. Then I tripped over this little note buried deep inside a zip file.
This SoftDevice release has internal changes that requires that the SoftDevice
is programmed onto the chip in a specific way. The following Nordic tools
– nrfjprog version 5.0.1 or higher
– nRFgo Studio version 1.17.0 or higher.
So maybe the tools for loading s120 and s130 code from the IDE need upgrading.