Hello Sergio,
A quick note, it seems that the Reply button on the website does not work with gmail (only internet explorer actually responded to the mailto link but did not let me send anything).
As I do not use email client software I had to reply by sending this email to lwip-users again.
As I noted in the email I sent previously, I have tried many ways of closing the connection.
Not closing it on a tcp_err call is one of those ways.
When not closing the connection on tcp_err I receive the same error:
Assertion "detected memp overflow in pool 0" failed at line 262 in ../lwip/src/core/memp.c
Also when I try to connect to the webserver after 1 failed connection the watchdog gets triggered and the system reboots.
I have to conclude that closing the connection on a tcp_err is not the problem.
Fabian