Not able to telnet to modems with dynamic IP

We have a fleet of modems set up for dynamic DNS using IP Manager. Since early June, we cannot log into these modems through telnet or web AceManager. But they are ping-able and we can tell these devices can communicate with our server. We also have some modems with static IPs. They don’t have the issue.

Any help will be appreciated.

Hi @tang.lei
Could you please share with me some information as below:

  1. On the failure devices, do you using log in to ACEmanager via Etherner’s IP address?
  2. On the good devices, are they using the static IP address provided from SIM? do you log in to them via that static IP?


About one week ago the IP Manager DDNS had trouble (IPs was not updated) but it is now corrected. The IP addresses are changing who often by your ISP ? For my it is every 24h but if the changes are rare and the “IP Manager Server (number) Update” is configured to “Only On Change” or if update period is incredibly large it is possible the IP was not updated.

You see your IP respond to ping but are you sure it is your device ? IP are reassigned to an other client very quickly and it is very common (for me) to fall on someone else device if DDNS is not updated or if my device is offline for any reason.

If your device makes connection to a server you should read the logs to verify the IP address you have with DDNS is the same you get form the server’s logs. With this IP you will be able to connect to the device.

It also can be friend list (list of IP authorized to connects to your device) misconfigured.

@jerdung, thanks for your reply.

  1. we tried both the domain name and the IP address, which we got by pinging the domain.
  2. yes, the static IP address is provided from SIM. We log in using the static IP.

@rmelior, Thanks for your suggestion.
Sometimes I also end up on other people’s device when trying to telnet to our modem. I assumed it was because the server was not updated.
I’m not sure how “Server Update” is configured on our modems. But most likely it’s “Only On Change”.
I’ll check the logs on the server. Thanks.

Hi @tang.lei ,
Theoretically, you should be able to access ACEmanager via Etherner’s IP you have pinged. So in this case please check port policy for port 9443. Port 9443 is default port to access to ACEmanager.

Hi @jerdung , @rmelior , sorry for the delayed response. I finally get the server logs. I confirmed the modem IPs returned by DDNS were not correct. I was able to log into the modems using the IPs recorded in the logs. The issue is IP Manager Server was set to, which apparently does not work anymore. I changed it to and It’s working perfectly. Thanks for your advice.