Re: [lwip-users] ERR_MEM when sending large data, LWIP stats show no error

[Sergio R. Caprile]

Ha, I love the word "severe" being used here...
I don't know, I've read some guys finding bugs on the Cube drivers, and 
seems to vary depending on which micro you are using. Search the list.
The fact is that your messages are getting lost and you need to find 
where...
I suggest running an echo with your current configuration. This way we 
can discard your application doing something nasty.
I'm not good at reading the stats, try enabling some TCP and netif stats 
to see if you find discards/drops/ or anything leading that way. I would 
blame the driver but I'm baffled by the correlation to TCP_SND_BUF being 
twice TCP_MSS. Perhaps Simon or one of the developers has an idea. I 
would check how TCP splits your data into wouldbe frames, maybe the way 
you partition gives the driver some fresh air not to drop frames... I 
don't know. Most of the times is a vendor fault so I'm biased here.