Lots of issues

Hi

I'm running an M1 MacBook pro and Serato, using the clubs cdj 2000 nexus and djm 900 nexus. about a year ago, when connected and loading tracks, Serato and my laptop would freeze for a couple of seconds.

Also, all of a sudden after a year of playing at the club, both the cdj 2000 nexus started to not connect. No matter what I tried, I could not choose a deck number when pressing link.

I wanted the left deck as deck one and the right deck as two in Serato. However, it would just set themselves as 2 and 3 and not work what's on my screen.

After several tries, re starts, software closes etc., usb port changes, it would eventually set itself correctly. I don't know how or why, it just would.

Now, all of a sudden, when both decks and mixer eventually connect, I get sound pops when a track is playing, maybe 3 or four big pops per track.

however, when I mix two tracks, or even touch the cue button on the other deck, I get really bad popping. Sounds like I'm playing old vinyl every time I mix.

I only have to touch the other deck, buttons, platter, and the sound distorts.

Also the sound quality is not too good.

I try to play with the latency setting in Serato, but it just makes the track play for a few seconds then turns into a digital distorted mess that gets worse and lower as the track plays on.

Does the djm act as the main connection? So, if it's not connecting properly the cdj's won't connect? If the mixer sound card is faulty, will the cdj's not work? I don't understand how it works.

Things I have tried.

Updated CDJ2000's to the latest firmware that's just come out.

updated mac os

updated Serato

bought a new faster external drive.

bought all new leads.

bought a new usb hub.

installed a fresh Mac Os, completely wiped old off.

had the MacBook tested by apple, all passed.

Works fine with my ddj sx, however sometimes freezes when loading tracks.

Any help would be appreciated.