A few days ago, I made a post in the Ubuntu MATE community subform with the same title, with the preface below:

"Hi all,

After a couple days of search, I haven't found anything regarding this issue regarding wired connection on the new 19.04 stable release of Ubuntu MATE.
For some reason, if I boot up my machine with my Ethernet cable plugged in, my wired connection will not work: even if I replug it, even if I tell my laptop to forget the network. However, if I boot up my system with my Ethernet cable unplugged, and then plug it it after it lands on the desktop, it works just fine.
The Wi-Fi works perfectly fine regardless.

With the occasional notification that I did disconnect from the network, and the WiFi indicator going through that pattern it does when it tries to connect, it appears as through it wants to connect, but something is blocking it from accepting the network.
What am I missing here?"

I had a moderator point me to around to different solution, but nothing has worked so far.
Link: https://ubuntu-mate.community/t/19-0...ore-boot/19333

I am confused because 18.04 and 16.04 has worked fine out-of-the-box. This is a particularly unusual glitch, I assume. I am looking for potential solutions here. Does anyone have any ideas?