XG135w connection breaking up


I'm experiencing sudden break ups witht he connection with my XG135w.

The configuration is as follows: ISP model with optical connection - unmanaged switch (with nothing else connected except ISP modem and XG) - XG - couple of switches with PoE and two Ubiquiti AP.

It all started on friday last week when I wanted to configure my two Ubiquiti APs with additional Guest WiFi network (with our existing one). After that the Ubiquiti APs started breaking up, so I deleted the newly created Guest WiFi, but after this I realised that our XG is always breaking up the connection to the internet. COuple of times it was WAN interface down, then it was okay but the connection was just broken for couple of seconds (without messaging that the WAN is down), then it went up for another couple of minutes, than breaks and so on (often with the message DNS_PROBE_FINISHED_NXDOMAIN after trying to refresh a site or to open a new one).

We have a ESXi on the network that has a AD virtual machine. The XG has a static DNS IP address set.

I'm not sure where to look at. It was all running smoothly before this Ubiquiti thing. Tried one more time to play with MTU (it was 1500) or to add a second rule to the WAN link manager for going down, but without help.

Any suggestions?

Thank you!

Edited tags
[edited by: Erick Jan at 12:17 AM (GMT -7) on 29 Jul 2022]

Top Replies

  • in reply to Shteki +1 suggested

    Hey ,

    Thank you for the update, use global DNS in DNS 1 preference following with the mentioned one. 
    Under the WAN Link manager under the failover gateways > edit the failover rules and with…

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  • Regaridng the switch - it's an unmanaged swithc, I've red somewhere here on the forum that I could help regarding often breakups with the connection.

    One more thing, the ISP modem is connected to another subnetwork, where the DHCP is in ISP modem range (192.168.1.x) and internet is working there without problems.

  • Thank you for the update. So the XG is actually not connected to the internet but via a modem which hands out IP (DHCP) addresses. Is there any chance the lease time of the DHCP on the modem is expiring and the XG is not renewing the address correctly?


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  • Hi rfcat_vk,

    that's right, it has an ISP modem with the intern address that has 4 ports, and one of them is connected to the WAN port of XG, where WAN is set to

    It has DHCP from to 254, from .1 to .99 is static. The problem is, the ISP doesn't want to give direct access to the router, I can only tell them what to do, they must configure it on their own.

    Since the addresses are static, there aren't any lease times here, so I supose.