Failed to get objects: Unable to connect to the in backend

Hi.
I recently updated my version of ChecK_MK from version 1.5.0p2 to 1.6.0p8.
I have configured distributed monitoring with a slave server where I enabled encryption using TLS on the connection and checking the “Verify the Livestatus server certificate using the local site CA” checkbox.
All good until this step, because Distributed Monitoring works well.

But in Nagvis when I want to get a host from that slave server, it shows me the following error seen in the screenshot:

Screenshot_5

Please help me with this. I have tried several options but they have no effect.

Master version: 1.6.0p8
Slave version: 1.6.0p6
Nagvis version: 1.9.17

One information what would be good for troubleshooting is the operating system version.
NagVis uses the system side PHP and if there is a problem with the SSL libs then you have this problem also inside NagVis.