Dear Strahi, I tried rtl8139. The behavior is the same. Best, Latcho From: Strahil <hunter86_bg@yahoo.com> Sent: Sunday, January 12, 2020 1:19 AM To: Latchezar Filtchev <Latcho@aubg.bg>; users <users@ovirt.org> Subject: Re: [ovirt-users] Unstable VM network connectivity after upgrade 4.2.8 to 4.3.7 Hi Latcho, Most probably it's a bug. Have you tried virtio and/or rtl-based NIC ? As far as I know, CentOS 5 supports Virtio after Kernel >= 2.6.25 . Best Regards, Strahil Nikolov On Jan 11, 2020 19:54, Latchezar Filtchev <Latcho@aubg.bg<mailto:Latcho@aubg.bg>> wrote: Hello Everyone, I am aware my guest OS is out of support but I experienced the following: oVirt – 4.2.8 (self-hosted engine) VM – CentOS 5.2; two VNIC’s ( driver used e1000) connected to different VLAN’s; - no issues with network connectivity After upgrade to oVirt 4.3.7 The same VM starts normally. Network is available for several seconds (10 – 20 pings) and then it disappears. The machine works but no ping to/from VM. When I am returning the same machine (via export domain) to oVirt 4.2.8 environment – it works as expected. Can someone advise on this? Any help will be greatly appreciated. Thank you. Best, Latcho