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on Amazon EC2 I want to set up multiple IPs on secondary Network Interface.

whatever I do it sometimes fail to connect to secondary IPs, main word here is sometimes, thats why its very complicated to pinpoint whats the issue...

here is my current setup:

EC2: m5.large

Ubuntu 18.04 - so using netplan.

1st Network interface eth0 has 1 private and 1 elastic IP, it works all the time, no issues there. eth0 setup:

root@multi-ip-host:/etc/netplan# cat 50-cloud-init.yaml 
network:
    version: 2
    ethernets:
        eth0:
            dhcp4: true
            match:
                macaddress: 02:19:c1:0c:e8:a0
            set-name: eth0

also private IP for the eth0 is: 10.20.0.45

2nd - ens6 has multiple IPs set up like this:

root@multi-ip-host:/etc/netplan# cat 51-ens6.yaml 
network:
  version: 2
  renderer: networkd
  ethernets:
    ens6:
      addresses:
       - 10.20.0.11/20
       - 10.20.0.198/20
       - 10.20.0.22/20
      dhcp4: no
      routes:
       - to: 0.0.0.0/0
         via: 10.20.0.1 # Default gateway
         table: 1000
       - to: 10.20.0.11
         via: 0.0.0.0
         scope: link
         table: 1000
       - to: 10.20.0.198
         via: 0.0.0.0  
         scope: link 
         table: 1000
       - to: 10.20.0.22
         via: 0.0.0.0
         scope: link
         table: 1000
      routing-policy:
        - from: 10.20.0.11
          table: 1000
        - from: 10.20.0.198
          table: 1000
        - from: 10.20.0.22
          table: 1000

each of the private IPs have elastic IPs attached. The issue is, that after set up, there may be 0 or more IPs that I can connect to. Then after reboot, there may be different IP that I can connect to from the 2nd interface, but cant connect to others.

What I am doing wrong?

UPDATE: I have added more static IPs to the eth0 and they all work 100% of the time. On ens6 left only 1 IP - and it seems its working 50% of the time... each time after running netplan apply I have approximately 50% chance to connect to that secondary Interface's IP from my machine. I do no other changes on aws, so to limit and narrow down possibilities on what can be wrong.

I can understand that if I do an error in the script it should either work or not 100%, but thats not the case here.

Is there anything fundamentally wrong how I set up ens6 in this script?

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