Problem with local Discovery in tinc-pre

[muh Kuh]

I'm currently running tinc-pre6 on 2 nodes in a larger network.
My Laptop (Lassulus), lan ip: 192.168.2.100, tinc-ip: 10.243.0.2
My Server (alphalabs), lan ip: 192.168.2.103, tinc-ip: 10.243.1.10
internet vserver (slowpoke), no lan ip, tinc-ip: 10.243.232.121

Everything works fine until both nodes are in the same LAN. The first
2-3 minutes everything is fine. Pings between the machines go through
other servers so they are between 50-80ms, 0% packet loss.
But as soon as localDiscovery starts to kick in the pings drop to 20ms
(which is good) but packet loss goes up to 90% (tested with ping -f).
For every lost packet tincd (started with -D -d4) shows the Error:
"Received UDP packet from unknown source 192.168.2.103 port 655".
Every 2-3 seconds the packet loss stops and tincd reports: "UDP
address of alphalabs set to 192.168.2.103 port 655"
But after <1second the packet loss begins again with the unknown source error.

log snippet:
UDP address of alphalabs set to 192.168.2.103 port 655
UDP address of slowpoke set to 81.89.96.210 port 655
Received UDP packet from unknown source 192.168.2.103 port 655
Received UDP packet from unknown source 192.168.2.103 port 655
Received UDP packet from unknown source 192.168.2.103 port 655
Received UDP packet from unknown source 192.168.2.103 port 655
Received UDP packet from unknown source 192.168.2.103 port 655
UDP address of alphalabs set to 192.168.2.103 port 655
Received UDP packet from unknown source 192.168.2.103 port 655
Received UDP packet from unknown source 192.168.2.103 port 655
Received UDP packet from unknown source 192.168.2.103 port 655
Received UDP packet from unknown source 192.168.2.103 port 655
UDP address of slowpoke set to 81.89.96.210 port 655
UDP address of alphalabs set to 192.168.2.103 port 655

ping output:
20:42:21 @Lassulus ~ ping -i 0.2 10.243.1.10
PING 10.243.1.10 (10.243.1.10) 56(84) bytes of data.
64 bytes from 10.243.1.10: icmp_seq=1 ttl=64 time=1.88 ms
64 bytes from 10.243.1.10: icmp_seq=3 ttl=64 time=1.88 ms
64 bytes from 10.243.1.10: icmp_seq=4 ttl=64 time=1.71 ms
64 bytes from 10.243.1.10: icmp_seq=8 ttl=64 time=1.97 ms
64 bytes from 10.243.1.10: icmp_seq=9 ttl=64 time=2.66 ms
64 bytes from 10.243.1.10: icmp_seq=10 ttl=64 time=1.71 ms
64 bytes from 10.243.1.10: icmp_seq=11 ttl=64 time=1.82 ms
64 bytes from 10.243.1.10: icmp_seq=12 ttl=64 time=3.06 ms
64 bytes from 10.243.1.10: icmp_seq=13 ttl=64 time=1.92 ms
64 bytes from 10.243.1.10: icmp_seq=14 ttl=64 time=1.85 ms
64 bytes from 10.243.1.10: icmp_seq=15 ttl=64 time=1.78 ms
64 bytes from 10.243.1.10: icmp_seq=16 ttl=64 time=1.65 ms
64 bytes from 10.243.1.10: icmp_seq=17 ttl=64 time=1.59 ms
64 bytes from 10.243.1.10: icmp_seq=18 ttl=64 time=1.92 ms
64 bytes from 10.243.1.10: icmp_seq=19 ttl=64 time=1.64 ms
64 bytes from 10.243.1.10: icmp_seq=20 ttl=64 time=9.77 ms

Lassulus tinc.conf:

Name = Lassulus
Device = /dev/net/tun
LocalDiscovery = yes

#ConnectTo = alphalabs
ConnectTo = slowpoke


Alphalabs tinc.conf:

Name = alphalabs
Device = /dev/net/tun
LocalDiscovery = yes

ConnectTo = slowpoke


Lassulus hostsfile:

Subnet = 42:0:0:0:0:0:0:dea7/128
Subnet = 10.243.0.2/32
Compression = 9
-----BEGIN RSA PUBLIC KEY-----


Alphalabs hostsfile:
Subnet = 42:0:0:0:0:0:0:a1fa/128
Subnet = 10.243.1.10/32
-----BEGIN RSA PUBLIC KEY-----