Cannot ping outside world from instance about coa HOT 1 OPEN

Openstack host uses NAT (192.168.149.0/24) interface, supposed to be used for Openstack management instead of br-ex interface (192.168.0.150) bridged to external network 192.168.0.0/24:

[root@devstack1 ~]# ip r

default via 192.168.149.2 dev ens36
10.20.20.0/24 dev ens37 proto kernel scope link src 10.20.20.129
169.254.0.0/16 dev ens33 scope link metric 1002
169.254.0.0/16 dev ens36 scope link metric 1003
169.254.0.0/16 dev ens37 scope link metric 1004
169.254.0.0/16 dev br-ex scope link metric 1008
192.168.0.0/24 dev br-ex proto kernel scope link src 192.168.0.150
192.168.149.0/24 dev ens36 proto kernel scope link src 192.168.149.128
[root@devstack1 ~]# ping 192.168.0.254
PING 192.168.0.254 (192.168.0.254) 56(84) bytes of data.
64 bytes from 192.168.0.254: icmp_seq=1 ttl=64 time=3.91 ms
64 bytes from 192.168.0.254: icmp_seq=2 ttl=64 time=0.422 ms
64 bytes from 192.168.0.254: icmp_seq=3 ttl=64 time=0.346 ms
64 bytes from 192.168.0.254: icmp_seq=4 ttl=64 time=0.911 ms
^C
--- 192.168.0.254 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3004ms
rtt min/avg/max/mdev = 0.346/1.399/3.918/1.470 ms
[root@devstack1 ~]#

---------------------
br-ex is already configured for IP and GW:

cat /etc/sysconfig/network-scripts/ifcfg-br-ex

DEFROUTE="yes"
PEERDNS="yes"
PEERROUTES="yes"
UUID="da67051d-85ca-4841-b877-b9ff16e935a3"
ONBOOT="yes"
DEVICE=br-ex
NAME=br-ex
DEVICETYPE=ovs
OVSBOOTPROTO="none"
TYPE=OVSBridge
OVS_EXTRA="set bridge br-ex fail_mode=standalone"
IPADDR=192.168.0.150
NETMASK=255.255.255.0
GATEWAY=192.168.0.254
DNS1=192.168.0.254

from coa.