I had a similar issue with my wired connection. It turned out to be a faulty old cable. Old cables can apparently start to have some signal stability issues due to age. For me, Win10 worked fine, even if the connection wasn’t as fast as it should’ve been, Manjaro with KDE sometimes claimed limited connectivity and at others no connection.
What I’m aiming for here is: Do you have a cable going from your router to a wall socket and how old is that cable? I felt it was a really dumb idea at first when it was suggested to me, but replacing the cable solved the problem and also all speed issues were solved.