[CentOS] After upgrade to CentOS 8.1 default gateway missing

> On Thu, 16 Jan 2020 15:34:43 +0100, Stephen John Smoogen
> <smooge at gmail.com> wrote:
>
>> On Thu, 16 Jan 2020 at 07:58, Asle Ommundsen <aommundsen at gmail.com>
>> wrote:
>>>
>>> Hi,
>>>
>>> Tonight I upgraded two CentOS 8 boxes to CentOS 8.1 (1911). Then after
>>> a
>>> reboot of the first server the network was unavailable. In IPMI console
>>> everything except the network was looking good. Network was
>>> unreachable.
>>> No errors in NetworkManager. I also restarted NetworkManager, but it
>>> did
>>> not help. Then I discovered that the default gateway suddenly was
>>> missing.
>>>
>>> Then I rebooted the server one more time, but network was still down.
>>>
>>> Then both myself and a technician in my datcenter was debugging this (I
>>> had to wake him up in the middle of the night, costing me a lot of
>>> money),
>>> without finding any reason for why the default gateway was missing
>>> after
>>> reboot.
>>>
>>> Then we rebooted the server a third time, and all of a sudden the
>>> problem
>>> was gone and the default gateway was back. [...cut...]
>
>> In order to determine what is going on you need to give a lot more
>> information.
>>
>> 1. How do these boxes get their network information? DHCP or static
>> 2. If they are static, what controls the setting of ips:
>> NetworkManager or network-scripts
>> 3. If they are static, how are they set in
>> /etc/sysconfig/network-scripts/
>> 4. Do the files in /etc/sysconfig/network-scripts list a GATEWAY=
>> 5. If you are using network-manager, what does nmtui or the graphical
>> tool say the gateway or default route is?
>
> Here is answers to your list. I have anonymized the some of the data:
>
> 1) Static ip configuration
>
> 2) This should be NetworkManager.
> nmcli output:
>
> eno1: connected to eno1
>          inet4 1.1.1.234/29
>          route4 1.1.1.232/29
>          route4 0.0.0.0/0
>
> eno2: connected to eno2
>          inet4 192.168.0.5/24
>          route4 192.168.0.0/24
>
> [root at server ~]# nmcli d show | grep IP4.GATEWA
> IP4.GATEWAY: 1.1.1.1.233
>
> 3)
> TYPE=Ethernet
> PROXY_METHOD=none
> BROWSER_ONLY=no
> BOOTPROTO=none
> DEFROUTE=yes
> IPV4_FAILURE_FATAL=yes
> IPV6INIT=yes
> IPV6_AUTOCONF=yes
> IPV6_DEFROUTE=yes
> IPV6_FAILURE_FATAL=no
> IPV6_ADDR_GEN_MODE=stable-privacy
> NAME=eno1
> UUID=1f9ec889-3c64-470a-894b-05543ee44c29
> DEVICE=eno1
> ONBOOT=yes
> IPADDR=1.1.1..234
> PREFIX=29
> GATEWAY=1.1.1.233
> IPV6_PRIVACY=no

Anything in the logs about what was going on? If you reboot this server
again and again, does the problem show up again?

Regards,
Simon