Thanks for sticking with me,  some comments below ...

Not sure, but electronics don't clear up memory in Restart, because electronics don't power down. However, that doesn't tell anything about the OS using any of the non-cleared memory in RAM. It doesn't make any sense that Reboot would use non-cleared memory - for me, that is. This may also depend on whether you have a memory check activated in BIOS and whether it does it, in the case of Reboot ... in cold Restart, it obviously always does. Doesn't make sense to me either, just saying what I see. 

What does VMware virtual hardware do in this case - no clear idea why it would be different to physical hardware. Maybe some developer can clarify this? Since Windows 10 VM shutdown, still, after a long time, locks up Linux hosts, from time to time AND Win11/Linux VM NEVER does that, there might be something funny going on in Windows 10 Shutdown OR its implementation in VMware. Just speculating.

Your case was about a Windows VM reboot, not the physical reboot.  The host is Windows, the guest VMs are Linux.

As for what can be done for RAM, well, not sure if this relates to this problem or not, but since you asked ...:

- obviously, I have no idea in what kind of memory allocation we are now. For large datasets 128 GB may be required - for moderate use, 16 GB is plenty.  128Gb  Ha!  I wish.  No, it's nowhere near that.  Host has 32Gb.  VMs mostly around 8Gb.  I tend to run two or three at at time.  But have tested with just one and same issue. So I guess we can rule out using too much memory.

- you can add memory. Or if its a "market PC", all the slots are filled and you have to substitute everything with bigger RAMs. Relatively speaking, they don't cost that much. Decent memory for a modern workstation motherboard, is about 80 euros per 16 GB. I would expect the same in dollars. There is no reason to buy a newer PC because of lack of memory. Check what your max is - 10 years ago 16 GB - later 32 GB - nowadays 64/128 GB, but check to make sure.

- as for memory config, do the following:

   a) make sure that you NEVER run out of memory on the physical computer. If you do, everything will lock up and getting rid of that situation may take some time or take a hard reset of the entire system. Count the memory allocation of your running VMs and add something for the Host OS (like 4-6 GB for Win10, depending largely what you do there, if anything). Observe the swap (in Task Manager) use to make sure. 

  b) check that the memory allocation of each VM that you use, is sufficient. Use Task Manager to find out. Do NOT exceed the physical memory of your physical computer.

 c) run less VMs at the same time, if not possible to commit the changes mentioned above

 d) try to run less applications at the same time. Internet browsers can steal lots of memory. Run them on a different computer. Observe all the other applications and their memory consumption. For instance, database applications, like Oracle, can allocate lots of memory, which they don't actually need for their operations (highly dependent on what you do).

Thanks for the advice. You are totally right of course, but I have the PC I have and I want to run the VMs that I have. So long as restart keeps getting me connections, I guess I can cope.