Boot up from cold boot no network

[Jim]

A few months ago my Dell Optiplex 7010 running Ubuntu 20.04 started 
booting up without the network.  I'd reboot the machine and  the network 
was there.  If I shut down the machine and turned it on again, no 
network.  I thought something was wrong with the built in ethernet 
adapter, so I bought a usb adapter, disabled the built in one and the 
problem went away until today.  Now it's happening with the usb ethernet 
adapter.  Rebooting the machine fixes the problem gets the network up 
and running.  If I start with a cold boot and reboot at the grub screen, 
I get the network.  I have 3 SSDs and 2 HDDs.  I have the same video 
card that I had before this problem first showed itself.  It's a GeForce 
GT 710.

I looked online and found something telling of other people who have had 
this problem.  They disconnected video cards and went back to the built 
in video (display port), and removed hard drives that had been added 
later and this fixed the problem.  The ultimate solution was to replace 
the power supply.  I disconnected one SSD and the 2 HDDs.  I don't have 
anything that can use a display port, so I left the video card in 
place.  All I had connected were  2 SSDs.  One it boots from and my home 
directory is on the other.  The problem still showed itself when I 
booted the machine, so I shut down and plugged in everything again.  
This thing has a 240 watt power supply.  Do power supplies go band in 
such a way they don't produce the amount of power they used to?

Any ideas what it might be?  Is there a command that would tell the 
system to set up the network again?  If there is, I could put it in the 
.bashrc until I get this fixed.

Thanks