Number of concurrent TCP client connections?

[thjean]

With the current implementation, it looks like the number of concurrent TCP client connections is limited to a total of 5.
Is there a known way to increase the number of allowed TCP client connections?

[earlephilhower]

I'm traveling so can't verify the number, but you can use the large TCP options on the menus (32k) to get more PCBs. You can also build your own libpico and change lwipopts.h in tools/libpico

[thjean]

Thank you for the hint on changing the lwipopts.h in tools/libpico and rebuilding the lib.
By replacing the entire lib folder by the rebuild folder, my sketch compiles and runs fine with more PCBs when build in the Arduino IDE. However, when trying to do the same with PlatformIO (using your core), the build fails with an undefined reference to `tusb_init'. By just replacing libipv4.a, the PlatformIO build does not fail. (I'm running Windows10 and used WSL for building the lib)

[thjean]

After applying yesterday's platform-raspberrypi patch ("Update to Arduino-Pico 4.5.1 with new boards"), the build issue seems to be solved.

[thjean]

Thanks a lot, using the 32k TCP option in the Arduino IDE gives me 10 TCP client connections. I did not notice that option as I was running Platformio. Unfortunately, it doesn't seem to be as easy as just adding "-D__LWIP_MEMMULT=2" to the build_flags in Platformio.
As I now know where to look for, I'll find a way to get this working.