NetXMS Support Forum

On what operating system do you run the management console?

Upgrade both, just to be on the safe side.

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Was it the same with a previous version of NetXMS, or you did not use it before?
This may happen, if your computer is switching from network to network, e.g. from ethernet to wifi. Also try pinging netxms server from your desktop to check that there are no connectivity issues.

There are thought to improve the protocol between management console and the server, one day this should be done, but not very soon.
Also, you can deploy web interface on the server. Communication with the web interface might work better in non-stable network.

Стоит помониторить память, потребляемую процессом netxmsd (агентский параметр Process.VMSize) и вообще свободную память. Один из вариантов - oomkiller - штука в линуксе, которая убивает процессы, если в системе заканчивается.
Еще можно запустить netxmsd не через systemctl, а в интерактивном режиме - это когда он лог в консоль пишет
netxmsd -D 5
цифра после D - уровень отладки. При этом netxmsd завершится если отключиться от консоли, нужно или держать соединение, или воспользоваться screen. После вылета посмотреть, может быть в консоли будет какая-то информация.

When NetXMS server starts, it makes a record in the database to mark that it's locked. This is to avoid another copy of NetXMS server to start on the same database. NetXMS server should remove this mark when it's being terminated, but sometimes, it does not happen.
You can unlock the database by issuing
nxdbmgr unlock

Something like this happens if lauching the installer directly from Firefox after download. Try running downloaded exe from windows explorer.

From first glance looks like it's pinging the interface and gets reply:
[19.11.2020 08:41:09]    Starting status poll on interface lte1
[19.11.2020 08:41:09]       Current interface status is NORMAL
[19.11.2020 08:41:09]       Starting ICMP ping
[19.11.2020 08:41:09]       Interface is NORMAL for 3763 polls (1 poll required for status change)

If you open Object Details for lte1 interface, does it has correct IP address? Could it be, that server can ping that address by some other route?

Try collecting server log at debug level 7 for the duration of status poll.

The DCIs you mention are not collected by SNMP. These are generated by NetXMS server while it's pinging nodes (see https://www.netxms.org/documentation/adminguide/icmp-ping.html#icmp-response-statistic-collection).

There should be some other reason why this router is not showing as down. Could be the correlation mechanism.
1) Show the output of status poll for this node.
2) Try temporarily increasing debug level to 6 or 7 for the server for the moment when this node goes from to down and show server log.

Please give some more details. Is there NetXMS agent or SNMP on that node?
If there's not, it's the default behavior of NetXMS - it will be pinging the node and showing that it's down.
If yes, would be interesting to know the use-case for that configuration.

Что-то такое должно помочь:

sudo apt-get install winbind libnss-winbind

sudo vi /etc/nsswitch.conf
исправить
hosts: files dns
на
hosts: files dns wins

Подробнее тут:
https://askubuntu.com/questions/27541/why-cant-my-machine-resolve-local-windows-hostnames

The names of parameters changes at some point. A newer template version is shipped, but NetXMS with default settings does not overwrite the templates (with the idea that user could have changed the out of the box templates).
It's Server Configuration setting "ImportConfigurationOnStartup". By default it's "Only missing elements", so you can either delete the template and restart the server (but you will loose DCI history), or you can set it to "Always" and restart the server.

The third option - you can import that template manually (Tools -> Import Configuration), here's the file: https://raw.githubusercontent.com/netxms/netxms/master/contrib/templates/netxms_server.xml

The issue is fixed and will be available in 3.6 which will be released this week.

Да, я не очень разбираюсь в Tomcat, но это ж форум, тут любой может высказаться.

Веб интерфейс с какой-то определенной версии NetXMS перестал работать с 7 Tomcat, нужен 8-й. Какая у вас версия NetXMS и что именно вы хотите поставить - web интерфейс или web api - не очень понятно. Ну и в целом - поддержка на Centos 7 гарантированно обеспечивается только для коммерческих клиентов: https://www.netxms.org/documentation/adminguide/installation.html?highlight=tomcat#operating-system

Веб интерфейс это вот это: https://netxms.org/download/releases/3.5/nxmc-3.5.90.war
а у вас в файлике написано NetXMS REST API - это по идее другя вещь - WEB API.