Thanks for pointing me in the right direction. The ESP8266 SDK Programming Guide explains some of the calls, and some experimenting shows it's set to 5 by default, and can be pushed to 15.
Code: Select all uint8 mc = espconn_tcp_get_max_con();
Serial.printf("espconn_tcp_get_max_con -> %d\n", mc);
sint8 rc = 0;
for (uint8 i = 8; i<26 && rc >= 0; i++) {
rc = espconn_tcp_set_max_con(i);
uint mc = espconn_tcp_get_max_con();
Serial.printf("Set max to %d", i);
Serial.printf(" -> %d, max %d\n", rc, mc);
}
espconn_tcp_get_max_con -> 5
Set max to 8 -> 0, max 8
Set max to 9 -> 0, max 9
Set max to 10 -> 0, max 10
Set max to 11 -> 0, max 11
Set max to 12 -> 0, max 12
Set max to 13 -> 0, max 13
Set max to 14 -> 0, max 14
Set max to 15 -> 0, max 15
Set max to 16 -> -12, max 15