Problem with 'slider' on my showcase theme

Hello all, I hope somebody can be help me, thanks in advance.

If you visit my site at https://www.dannylennonmotion.com, for me on my iMac, macbook pro and iPhone the top ‘slider’ on the mac screen doesn’t work.. Its obviously meant to slide between the projects. But i believe it does work for a few friends of mine when visiting my site.

Also when i view the following 2 sites which also use the same theme I do, theres don’t work.

https://covergraphix.com/covergraphics/

https://www.ents-unltd.com/

Now my question is, even when i use a different computer on a different internet network etc etc, sometimes they work and sometimes not.

I had never had a problem before, and well its very very confusing. Is it my site or is it something to do with the networks I am using? If everybody replys in here can see my site and the other 2 examples shown. I guess its a network problem at my end.

Thanks again.

Danny