Firmwarebug: M400 sometimes fails to send Ringing when M30 and A190 are paired

Hi all,

I'm having trouble operating a M400 with two M30 and a A190. One M30 is paired with the A190, the other M30 is connected stand alone.

Sometimes incoming calls start ringing but don't send the SIP status ringing back to the telephony provider (Deutsche Telekom). This happens only when calling the extension with the paired devices. Switching either the A190 or the M30 off makes the base station send the ringing status. The behavior can be observed both within the M400 SIP Log and on the wire using wireshark. A screenshot of wireshark follows.

Explanation: The first incoming call at packet 84 was signalled correctly by the unpaired M30. The second incoming call from packet 571 should have been signalled by the paired M30 and A190. Both were ringing indefinitely until I pressed the hangup button (packet 821). But the M400 didn't send out the Ringing-packet (should have been directly after packet 572) and therefore the telephony provider terminated the connection.

The firmware is up to date:

M400: 670B202
M30: 670B201
A190: 670B01 / VoicePrompts VP_A190_v0670_B0001.fwu

There is also a second issue I'm struggling with, which I'm unsure if it is related. The M400 status LED cycles its color with a frequency of about one change per second like green-red-yellow-green-red-yellow-...

When the LED cycling starts, syslog shows a critical log entry with the message "loc7 .Crit  2024-04-15T21:30:02.650Z  38 [ ERROR. LMX Rssi error. Total number of received errors since boot:3 ]". The number increases from time to time. The admin manual doesn't document this led indication.

Has somebody already experienced one of the issues described above? And hopefully has a solution?

Best regards
Christian

Update: the second issue seems to be resolved. I switched from external PSU to PoE and since then the "LMX Rssi error" didn't occur again and the LEDs don't cycle anymore.