I found reason why my telnet under PPP driver failed.
This is because I used netmask 255.255.255.255 :-(
But in ipin.c there is:
if (dst == 0xffffffff ||
(nif->if_local_ip && ((dst | nif->if_mask) == 0xffffffff))) {
bcast = 1;
.....
if (bcast)
NutNetBufFree(nb);
Now all works OK.
Best wishes,
Tarmo Fimberg