First, Thanks for waiting so long, we will spare no effort on assisting your issue.
But secondly may you elaborate the condition of the being worst skype, the lag of connection or the fluency of video, is the phenomena only appears on this Application or generally the System? Have you recently applied any changes to the PCs or certain PC, How many PCs is getting lagged with Skype.
And the most important thing, could you confirm which products are you using? for we have Skype and Skype for business, that's different story.
Hope this can help you
If your need further help, be free reply to me at your convenience.
If the Answer is helpful, please click "Accept Answer" and upvote it