Safari iCloud tabs not syncing across all devices
I have a Mac and MacBook running 10.15.7, iPad and iPhone running the latest iOS. The MacBook will not update to big surprise (too old)
The problem is The safari tabs do not show what are currently open on each device, even though handoff works fine. If I reboot the machine, the tabs update. However, the tabs start to become available, and all at once randomly. For instance, this morning tabs are showing on my iPhone, granted all out of date though. Two hours later, no iCloud tabs are available. Move to my Mac and they are available for a few seconds and then they disappear.
I have disabled safari in iCloud and re-enabled on all devices. Rebooted etc etc.
This can't be just because I have not updated my Mac to big sur, Apple say it is chatting to them.
What am I missing?