Hi juraj,
NR clients tries to establish UDP P2P connection with peers, it may downgrade to relay mode if failed. If there are symmetric NAT or restrict firewall rules between those peers, they would fail. If there are more than 2 NATs in front of a device, it depends on how busy those NATs. In your case, it is more like restric firewall rules block the P2P connection.
If you can change the firewall rule of your router and open a port range for NR clients, it would be able to establish P2P connection. then you may need to change teh Feature.ini file telling NR the port range.
Take a look at the port range setting in Feature.ini
http://www.neorouter.com/wiki/index.php ... ationFiles#Description: Min listen port when establishing P2P connection
#Options: 0 - use port allocated by OS; > 0 specify start port number of the port range, that is used by Client to establish P2P connections.
#Default: 0
MinP2PListenPort=0
Btw, the 400ms ping is too slow. Usually relay mode should not be that slow. Please check your NR server's performance or network speed.
Thanks,
KevinZ - NeoRouter team