connection error by more than 4 nodes

[deep_eye]

Hello again, now we have upgraded all tinc-nodes + master to version 1.0.13 and a completely new config generated.

master: has public ip-adress + tinc-port is reachable from internet, has public keys from all nodes
nodes: behind nat-routers, no port-forwarding enabled, has public keys from all nodes+master

node-tinc-config:
Name = node01
Interface = gaming
Mode = switch
MaxTimeout = 10
PingInterval = 120
ConnectTo = master

node-host-file:
IndirectData = yes
-----BEGIN RSA PUBLIC KEY-----

If 3 nodes are connected with the master, than the fourth node (regardless of which) has a problem:
1292443976 tinc.gaming[32450]: Error during decryption of meta key for node09 (188.22.118.129 port 60114)
1292443976 tinc.gaming[32450]: Error while processing METAKEY from node09 (188.22.118.129 port 60114)
1292443986 tinc.gaming[32450]: Error during decryption of meta key for node09 (188.22.118.129 port 60137)
1292443986 tinc.gaming[32450]: Error while processing METAKEY from node09 (188.22.118.129 port 60137)
1292443998 tinc.gaming[32450]: Error during decryption of meta key for node09 (188.22.118.129 port 60144)
1292443998 tinc.gaming[32450]: Error while processing METAKEY from node09 (188.22.118.129 port 60144)

My question: is it possible with tinc to connect all hosts without enable port-forwarding?
I have tested the config with my linux host and kvm. With kill -USR2 i saw, that all nodes have connections to the master but none to it's neighbor node.

master-log:
Edges:
master to node01
master to node02
node01 to master
node02 to master
End of edges.

node-log:
Edges:
master to node01
master to node02
node01 to master
node02 to master
End of edges.

greets Manuel