Can’t pair after changing network settings

I am having trouble with my remote switches. I am using all Legrand switches, and had everything working, but figured out that I had my network set up with too small of a subnet with only a mask of 255.255.255.0. So, I changed my network settings to a 255.255.240.0 network and changed the DHCP to match.

Then all my remote switches for the three-way controls all stopped working. They have no light on them, and do not turn the lights on or off. I power cycled all of them, but this did not change anything. The main switches all still work and appear on the Home app (except for the 14.2 glitches).

When I try to re-pair them, the green LED will flash on the remote, but then just goes out, back to no LED and no pair. I reset the remote switch and went through the wifi settings on my iphone to reconnect it to the network, and then tried pairing with the same bad results. I reset both the remote and main switch, reinstalled both, and still they remote will not pair. I also tried pairing the remote to another main switch that is in the same switch box with it, and it has the same behavior.

Is there some reason my remote will not pair? Is it because it cannot forget a previous setting?

What does it mean if it blinks green and then goes dark?

Is there some special reset that it needs, instead of just holding the switch paddle “on” until the LED turns yellow? (The alleged factory reset)

Is there a diagnostic utility for HomeKit that allows me to see the switch internal settings or do some config right on the switches?

Are there any known issues with remote switches and netmasks or certain IP addresses? SSIDs?

Any online resource that can help me? (I googled and looked at the WiKi here, but nothing seems to deal with this problem.)

Thanks in advance for your help!!!