Although each case with ‘yellow registration dots’ should be investigated individually, in general to investigate the cause why a device, which is configured to register with DNS-SRV, shows a 'yellow registration dot' the initial focus aims to the following three points:
1) custom changes to the device’s configuration:
The device’s configuration should be checked on your side via the web interface of the device. In case auto provisioning is used for the device, please make sure no changes were made to the device’s settings manually.
2) unsuccessful Registration attempts on DNS-SRV servers:
Success of Registration attempts on DNS-SRV servers will be checked on our side by capture the registration requests via a trace.
The procedure here is the following:
you let us know the time you noticed the registration dot of the device(s) turned to yellow;
we start a trace on the device;
you reboot the relevant devices and let us know the time the reboot was made;
we analyze the registration requests (attempts).
3) network connectivity problems causing the inability of the device to send successful registration requests to DNS-SRV server:
To evaluate the network performance on our side we can start a SmokePing. Nevertheless we cannot influence the customer’s network settings, therefore they should be checked by the network engineer.
Please note that some legacy DNS servers of customers (e.g. router, firewall, old Windows server or even Internet provider) may not support DNS-SRV. To verify this, please, configure the phones to use the DNS servers of Google (220.127.116.11 and 18.104.22.168) and check if the devices are registered at DNS-SRV.
If you change the DNS settings in the device, please also check the status page of the device. There you will find the DNS server used in the local network. If this points to the router, it is also a possibility to change the LAN DNS server address in the router itself. Please note that changing settings in both the phone and the router requires a reboot. By changing the settings in the router, the router might reboot automatically.