T46s - Re-registration delay SIP Server 2

[TVAdmin]

Dear all,

I have 2 Xivo PABXs running in High Availability and several Yealink T46s phones connected.
Whenever the master PABX goes offline (for test purposes I disconnected the NIC of the master), the T46s keeps trying to register to the master that went offline while the slave (SIP server 2) is available.
The whole process of the phone registering to the 2nd SIP server takes about 30 sec - 2 minutes which is very long.
This while all is still in a test setup in a closed network on the same gigabit switch.

I already tried to tweak the following values:
⦁ SIP Registration Retry Timer: interval (in seconds) for the to retry to re-register account when registration fails
⦁ Server Expires: registration expiration time (in seconds)
⦁ Server Retry Counts: retry times to resend requests when the SIP server is unavailable

This by having 1 phone set to the maximum value, 1 to minimum, 1 to default. But I couldn't see any difference. It seems that the Yealinks don't seem to understand the SIP Registration Retry Timer. Or am I expecting too much, is a 30 sec - 2 min registration normal when a Yealink has to re-register to a xivo (based on asterisk)?

FYI: Currently on firmware 66.84.0.15

If someone would have any idea in order for the phone not too continuously try to subscribe on the master wen it goes down, that would be great.

Appreciate all the assistance,

Kind regards,