I'm using internel J60 driver of PIC18F67J60 and TCP/IP Lite stack.
 
In source code of J60 driver,
// Note this driver is half duplex because the HW cannot automatically negotiate full-duplex
// If full duplex is desired, both ends of the link must be manually configured.
// the "out of box" experience dictates half duplex mode.
 
But, By default the source code is initializing to not half duplex mode.
Hmm,  If I want to ignore the above-mentioned condition, should I always use half duplex, unlike the default code ?

The current situation is as follows.
When I am using the default code of TCP/IP lite stack (FULL DUPLEX),
It seemed like there was no problem when using the 3com L2 switch (2024).
When using the ip time wired/wireless router, 2 out of 10 had symptoms that the ethernet could not be properly set up at boot time.
After changing to HALF Duplex, the two that were not setup successfully booted with the iptime router connected.

Even if I look closely at the code, it is not easy to pinpoint it.
Looking at the datasheet, it seems that additional coding is required to use full duplex, and there is no part for full duplex mode except the initialization part in the provided code.
Finally, I decide to use HALF duplex mode other the default mode (Full duplex) in the provided code.