I have a similar/same problem on my freshly installed 15.5 as described here for Tumbleweed:
On the network manager icon, there is an exclamation mark after system startup because the system is supposedly “unable to reach the internet”.
However, it works fine.
This was not the case with 15.4
sudo service network restart
the warning disappears.
Is this the same problem that was fixed with Tumbleweed, or is this something else?
Network manager is there a problem in 15.5?
and the corresponding bug report:
Bug 1212910 - “Limited connectivity” alert on both, wireless and wired connections
Thank you, I had not found that.