[SOLVED] Network broken in Linux guest

[kokoticek]

Latest Proxmox 5.3 VE updated through "apt update && apt full-upgrade" from 5.2.

Centos 7.6 x86_64 guest with paravirtualized (virtio) NIC.
Turned off Selinux and firewall.

Centos guest is unable to ping any device in physical LAN, except just a couple of answered pings, but less than 20%. Only can ping to Proxmox host itself.
The other LAN devices, all connected through ethernet cable, can ping Centos VM, but with ridiculously high latency (30-50 ms, when average device to device ping is average 0.6 ms).

Any ideas by chance?

 

[Stoiko Ivanov]

hm - any chance you have the IP twice in your network? (or the containers' mac)?

 

[kokoticek]

Yes!
It was indeed a duplicated IP address in the LAN!

Thanks very much sir. I had never ever seen the actual symptoms of a duplicated address inside a LAN...

 

[Stoiko Ivanov]

You're welcome! If you don't mind, please set the thread to SOLVED, that way other users know what to expect.
Thanks!