DNS servers are added in reverse order, so this may explain why you are having an issue.
Will be resolved in a future version of OSMC
Hi, Sam
It was a long struggle but I am glad that we found the reason why the clock was not synchronizing.
Thanks for the time that you all spend to the problem.
As I pointed out earlier - it’s a DNS resolution problem on your network. I would consider having two DNS severs assigned where one of the servers doesn’t actually work to be a problem. 
While it is a bug that OSMC uses dns servers in the reverse order assigned by DHCP, that just exposes broken dns servers that might have otherwise gone unnoticed. All your DNS servers should work, or they shouldn’t all be assigned.
Delays are inevitable when DNS has to fall back to secondary or tertiary servers.
Hello DBMandrake,
So now I also know that my router’s DNS address is not working.
What can I do to prevent that my router give it’s DNS address to the Wifi adapter as a second DNS address during DHCP setup?
This is the only option since you say you can’t change the options in the router.
Yes, I did change the primary and secondary DNS server settings in MyOSMC. So it now works till the next OSMC update.
I did looked one more time in the settings of my router and I found the fields for setting the primairy and secundairy DNS server settings, they where hiding beneath a button ‘more’. I change them to 8.8.8.8 and 8.8.4.4
We won’t touch your networking settings across updates.
@DBMandrake, I finally revisited the patch for this. I realised that my patch was only fixing the ordering for domains, not nameservers. I have sent you a revised patch in Slack.
Hello Sam,
I realise that, but its for me a control methode to see if the problem is really solved with the next OSMC update. After the OSMC update I switch the primairy and secondairy DNS server again to its original state and change the DNS settings in my router to the google settings. After all these actions the problem should be solved for the future.