How to speed up / force Lightroom Sync?

I know working between Classic and CC involves compromises.   I use CC on the iphone to take images and this time I selectively loaded a number of raw files from my DSLR to my iPad for some basic editing.  It all synced well over hotel WiFi’s to the CC cloud.  Now I’m home all I expected was to switch on Classic and wait for 600 original images,  (500 iphone + 100 RAF files approx) to sync and download.

Two days later and I still have only 400 downloaded.  When it syncs it is slow, but then it stops.  Attempts to force sync (an adjustment to an existing photo), closing and reopening Classic, rebooting the Mac) only occasionally work.

Why is it SO SLOW? And how can I trigger sync activity when it stops?  I dont want to load my camera images until sync has completed and this is driving me nuts.

I‘m on latest versions and with a broadband download of 75mbps / 20 up.  There are no error files in the sync queue. The Mac and Classic are set currently to be always on, no sleep.  Any thoughts anyone or am I naively expecting things to actually work well for my monthly subscription???