T42G DNS problem

[imarsu]

Hi

we have about 2000, T42G phone and now we encountered an embarrassing problem.
problem relates to the fact that the network in the DNS server is not available for 100%, and if present, the DNS does not work when the phone makes a SIP-server registration for reuse, it fails and the telephone remains in the "No Service" state.
and telephone recover from this, other than factory reset
even if the dns would be available again

t42G phone
Firmware Version 29.73.74.1
Hardware Version 29.1.0.0.0.0.0

and we have two DNS server primary and secondary

[Karl_Yealink]

The 29.73.74.1 is special version, so please contact the Microdata for help.
And please cc to elaine@yealink.com. Elaine is my colleague responsible for Microdata.
If the Microdata can't help you, my colleague will help you.
Any question, please let me know.