RB411U / M33G with R11e - rebooting

Hello.
I have got few configurations of RB411U or M33G boards with LTE modems - EC20 or R11e.
They are located in different locations in Poland. They have external outdoor antennas. LTE/3G RSSI is better than 70dBm.
Power supply is from Meanwell, 13,8V 150W (with battery backup) for other devices connected to Mikrotik. Everything was new. The oldest was installed one year ago.
Each Mikrotik is working with one ethernet device, connected by Ether LAN connector by 1 meter patchcord. It uses very low data transfer (200kbps max)
They aren’t hot, installed in air-conditioned rooms.

All devices are working fine. But first started to rebooting 3 months ago. When I changed it for new one problems stopped.
I’ve changed all parts (enclosure, board, modem and pigtail) and it is working fine to now.
Two months ago I’ve the same problem with another one device. I’ve replaced and it is ok.

The same one month ago, and the same today.

They was rebooting every 20-minutes, after one day it started to reboot more often - every five minutes), to be completely dead. It works only 10 seconds after manual reboot (unconneting from power supply)

Change 3G/2G or LTE in R11 changes nothing when Mikrotik is ‘broken’.
In log I can only see: Router was rebooted without proper shutdown, and later normal booting procedure to LTE network.

In today’s broken device I’ve upgraded firmware to 6.44.1.
Configuration is RB411U and R11e-LTE.



Can anybody helps ?
I think this device will be dead after this weekend. I’ve got 300km by car to change it.

More info.

I found one of “broken” Mikrotiks.
I’ve changed LTE modem to another one (new, from box) R11e-LTE.
It is working at my desk.
RSRP of LTE signal is about 96dBm, RSRQ=13dBm

Here is part of the logfile, when Mikrotik has been restarted:

Mar/23/2019 19:02:49 lte,async,raw lte1: sent AT+CESQ
Mar/23/2019 19:02:49 lte,async,raw lte1: rcvd +CESQ: 99,99,255,255,16,45
Mar/23/2019 19:02:52 lte,async,raw lte1: sent AT+EEMGINFO?
Mar/23/2019 19:02:52 lte,async,raw lte1: rcvd OK
Mar/23/2019 19:02:52 lte,async,raw lte1: sent AT+CESQ
Mar/23/2019 19:02:52 lte,async,raw lte1: rcvd +CESQ: 99,99,255,255,16,45
Mar/23/2019 19:02:55 lte,async,raw lte1: sent AT+EEMGINFO?
Mar/23/2019 19:02:55 lte,async,raw lte1: rcvd OK
Mar/23/2019 19:02:55 lte,async,raw lte1: sent AT+CESQ
Mar/23/2019 19:02:55 lte,async,raw lte1: rcvd +CESQ: 99,99,255,255,16,46
Mar/23/2019 18:36:35 system,error,critical router was rebooted without proper shutdown
Mar/23/2019 18:36:35 ntp,debug Wait for 0 seconds before sending next message
Mar/23/2019 18:36:35 ntp,debug,packet error sending to 194.146.251.100, restarting
Mar/23/2019 18:36:35 ntp,debug Wait for 0 seconds before sending next message
Mar/23/2019 18:36:35 ntp,debug Wait for 16 seconds before sending next message
Mar/23/2019 18:36:35 dns local query: #1 cloud2.mikrotik.com. A
Mar/23/2019 18:36:35 dns done query: #1 dns server failure

194.146.251.100 is Polish NTP (tempus1.gum.gov.pl)

So I think the problem is with Mainboard or configuration.