Ubuntu 18.04 can't access LAN resources

Hi, I am using Pop!_OS 18.04, I tried setting up, KVM, Docker (for lab), so that my media-server can run in a vm, however I never quite got the networking right. WAN network worked for host and guests, but LAN is inaccesible via the hostnames, (tried with another computer in the network and it works fine).After spending day trying to fix it, i reset my lab, thinking, maybe the problem arouse from the start.

Yes, after installing fresh Pop!_OS 18.04 with no software, I cant ping via hostname on the local network, outside for example google.com works fine.
I can nslookup the IP, and it returns the correct hostname, but nslookup hostname, returns SERVFAIL.

I tried to recreate the problem with Ubuntu 18.04, Xubuntu 18.04, problem persisted. I am currently on 19.10, cause maybe along with feature updates, this would also be fixed (wrong) same outcome.

This is a new system with Gigabyte b450m ds3h, the network chipset Realtek r8169

Has anybody experienced this problem? Maybe someone has already solved it?

What’s in /etc/resolv.conf. You should see at least
domain homenetwork

or something like that naming your local domain and the local nameserver. If you are on DHCP, these should be handed out, but you can check them here, and depending on your network tool, even set them correctly. NetworkManager will override this file however upon a new connection if you use that.

options edns0

It should however get it from the DHCP, should I set it to (it corresponds to my router)?

Yes, thank you very much, after changing to (that corresponds to my router it works),
Will it be persitent?

It depends if you are running NetworkManager. I am unfortunately not sure what networknig system that PopOS uses, but I have to assume it is. Upon reboot, or service restart, that will likely get reset. Go into your GUI network options and see if you can set the nameserver in there, or you could always do a manual network configuration if you so choose. I haven’t worked with NetworkManager in ages, so hopefully the GUI works, or someone else chimes in with an answer to that, but at least we know the general cause.

EDIT: Other thought. Go check your DHCP server and make sure it’s configured to hand out the correct addresses. If it works on all other machines, then I’m not sure.

It is running Network Manager, however, previously, when I was changing via the GUI, it didn’t change anything.
Even if it shows what I changed, but ignores changes, I even tried with netplan, but same outcome.

Nevertheless, thank you very much!