[member=3719]bfb[/member] your original post was made on July 01, 2018, 12:10:24 AM
10 hours later @ 10:05:02 PM you're complaining about lack of reponse !!!
On some forums with a much bigger membership threads never get answered or when they do it's with the refrain "RTFM"
not something I've ever seen on here.
So you should take into account everyone is a volunteer on here. LL is used worldwide so different time zones come into play. When someone posts a question, people could be sleeping, working, enjoying personal time with families, or even just taking a break from their pc and not know about your problems.
SO HAVE PATIENCE
Having said that, I'll take a stab at helping you with your problem. LL 4.0 is based on ubuntu 18.04 and this is something that happened when I tried Xubuntu 18.04.
At sometime ubuntu switched to using NETPLAN and .yaml config files for it's network configuration.
https://netplan.io/
For most people the .yaml file is created at install with no problem but sometimes it isn't. Even so, most programs will still work ok, browsers will still connect ok, as you have noticed using the terminal or synaptic works.
I think the problem lies in the error checking done throws up an error when the yaml file is incorrect hence your, not connected message.
How to test if this is your problem, right-click on your network icon in the panel and look under ethernet at the top. If it says device not managed then it's a good chance your yaml file is not correct.
I can't tell you what to write in your yaml file but do some reading on the above website. Examples are given and might solve you problem.
If this does not solve your problem then I do apologise for wasting your time with this long post