I installed Cloud Foundry on my old 8-core Linux box. Everything went fine to the point where I tried to access the installation.
Targeting the API failed with "host not found". I tried to dig api.10.244.0.34.xip.io but this failed.
The DNS settings on my machine came from my home router flashed with DD-WRT. I checked the DNS servers and found out that I'm using my Internet Provider's DNS servers. Blaming them I added Google's 18.104.22.168 as a third address.
I restarted the router and the computer (just in case) but the problem persisted. Searching the net provided me with a clue that DD-WRT has a problem with external DNS providers. I went for a solution that would enable only xip.io to resolve host names, so I would have a good protection against attacks.
However it turned out that adding rebind-domain-ok=xip.io to DD-WRT's DNSMasq config caused the DD-WRT DNS to stop functioning.
In the end it turned out that DD-WRT for my router does not seem to work correctly with custom DNSMasq config and a lot of people also suggested that.
So I ended up setting No DNS Rebind to Disable in the Services menu of DD-WRT.