OMS Gateway error.

[JoeShmo980]

We have setup some test machines and have OMS Gateway sitting on server 2019. £ have 3 test clients.

I rebooted the 2019 box the other day and now its failing to connect - Any ideas ?

I reinstalled the OMS gateway and these errors came up

[#2]

Hi Joe.
Are machines on-prem, azure?
Are they domain joined? Sometimes if you allowed outbound traffic to specific windows firewall profile, the default profile might change.
Did you tried to run TestCloudConnectivity tool?
The tool is installed by default with the agent in the folder %SystemRoot%\Program Files\Microsoft Monitoring Agent\Agent. From an elevated command prompt, navigate to the folder and run the tool. The tool returns the results and highlights where the test failed (for example, if it was related to a particular port/URL that was blocked).
Recheck if your workspace key has been regenerated recently.
You need to install the Microsoft Monitoring Agent on the Log Analytics Gateway and configure it with the same log analytics workspace that you will configure on the data collection machine.

[#3]

Hi, thanks for the repsonse. All servers are on prem. The gateway box is Server 2019 so doesnt have the Management Agent installed, I just ran the script from azure that turns it on (I believe its already has the functionality. ) So it was working for a bit, then failed for some reason. I came to a loose end and installed the management agent and it works.... Bizarre.

[#4 · Accepted solution]

@JoeShmo980 
At least by documentation its required on the following notes:

 
Note 1 - URL 1
The computer that runs the Log Analytics gateway requires the Log Analytics Windows agent to identify the service endpoints that the gateway needs to communicate with. The agent also needs to direct the gateway to report to the same workspaces that the agents or Operations Manager management group behind the gateway are configured with. This configuration allows the gateway and the agent to communicate with their assigned workspace.
Note 2 - URL 2

It is required to install the Microsoft Monitoring Agent on the Log Analytics Gateway and configure it with the same log analytics workspace that you will configure on the data collection machine.

Sometimes without all the pre-requirements stuff works when it shouldn't