Final 6.2.1 update causing LAN instability/sluggishness

I brought my RN312 to another site. It started up.
Rear panel Ethernet port LEDs are green on / green flashing permanently (hm, according to the hardware guide, it should be green blinking / amber off).
But since then, the internet router got into an infinite boot loop at this site too (AVM Fritz!Box 6360 cable).

I can log into Admin Page. The Network interfaces tab is empty.
Logs do not show any error messages.

I was able to make a ssh connection (takes a while) and execute top:

top - 15:04:40 up 44 min,  3 users,  load average: 2.07, 2.08, 2.11
Tasks: 172 total,   2 running, 170 sleeping,   0 stopped,   0 zombie
%Cpu(s):  8.7 us, 17.2 sy,  0.0 ni, 73.7 id,  0.0 wa,  0.0 hi,  0.4 si,  0.0 st
KiB Mem:   2038072 total,  2002548 used,    35524 free,     1604 buffers
KiB Swap:   523964 total,        0 used,   523964 free,   919672 cached

  PID USER      PR  NI  VIRT  RES  SHR S  %CPU %MEM    TIME+  COMMAND
 1715 root      20   0 23232 2412 2100 R  99.2  0.1  43:05.64 connmand
 2550 unifi-vi  20   0 2314m  49m  18m S   1.3  2.5   0:11.47 mongod
   15 root      20   0     0    0    0 S   0.7  0.0   0:05.99 ksoftirqd/2
 2221 mysql     20   0  475m  42m 6936 S   0.3  2.1   0:02.07 mysqld
 2236 unifi-vi  20   0 3657m 337m  16m S   0.3 16.9   1:39.43 jsvc
 2589 root      20   0  503m  55m  25m S   0.3  2.8   0:05.73 mongod
 5268 root      30  10 28556 1616 1132 R   0.3  0.1   0:04.88 top
    1 root      20   0 45624 4360 2004 S   0.0  0.2   0:02.76 systemd

Something seems to be wrong with this connmand.
I think it is some kind of network connection manager, but I do not have a clue.
The change date of /usr/sbin/connmand is 2014-12-17 02:46:07

Any idea, what I should do from this point on?


Kind regards, frantic