Join Skype for Business Meeting delay

Hi everyone,

I wonder if someone could help me. We‘re using Skype for business OnPrem 2019 and some of our customers complaining about joining meetings.
Sometimes it takes several minutes to let you join a meeting.
Have you ever experienced something like this delays?
We can’t really see anything on the Skype for business server. Could it be related to the hardware itself for example drivers?

Thanks in advance.