Trouble with Netplan YAML File for Adding Thrid NIC

[kalpana]

Ubuntu 20.04.6 LTS System with three NIC cards.

NIC 2 (a,b) & 3 are in bridge mode.

When NIC 3 was setup as a bridge on subnet 192.168.5.0 everything was working fine BUT when I attempted to change NIC 3 and set it up as a bridge on subnet 192.168.1.0 the ONBOARD NIC is unreachable from the LAN (192.168.1.0) .

Not sure what I am doing wrong and would appreciate some assistance.

1. Onboard NIC
aa:aa:aa:aa:aa:aa 192.168.2.2 <-- STOPS WORKING when SINGLE NIC bridge is set to 192.168.1.25

2. Dual NIC
(Port A ) bb:bb:bb:bb:bb:bb 192.168.3.2
(Port B ) cc:cc:cc:cc:cc:cc 192.168.4.2

3. Single NIC
dd:dd:dd:dd:dd:dd 192.168.1.25 <--- DOES NOT WORK
dd:dd:dd:dd:dd:dd 192.168.5.2 <--- WORKS


onboard-NIC.yaml

Code:

Code Select Expand

network:
  version: 2
  renderer: networkd
  ethernets:
    eth1:
      match:
        macaddress: aa:aa:aa:aa:aa:aa
      addresses: [192.168.2.2/24]
      gateway4: 192.168.2.1
      nameservers:
        addresses: [192.168.2.1]
        search: [localdomain]

singleNIC.yaml

Code:

Code Select Expand

network:
  version: 2
  renderer: networkd
  ethernets:
    eth4:
      match:
        macaddress: dd:dd:dd:dd:dd:dd

  bridges:
    br2:
      interfaces: [eth4]
      addresses: [192.168.5.2/24]    #If I switch this to 192.168.1.25 then the onboard NIC 192.168.2.2 is unreacable from the LAN
      mtu: 1500
      nameservers:
        addresses: [192.168.5.1]
        search: [localdomain]
      parameters:
        stp: true
        forward-delay: 4
      dhcp4: no
      dhcp6: no

dualnic-port-1.yaml

Code:

Code Select Expand

network:
  version: 2
  renderer: networkd
  ethernets:
    eth2:
      dhcp4: no
      match:
        macaddress: bb:bb:bb:bb:bb:bb
 
  bridges:
    br0:
      interfaces: [eth2]
      addresses: [192.168.3.2/24]
      mtu: 1500
      nameservers:
        addresses: [192.168.3.1]
        search: [localdomain]
      parameters:
        stp: true
        forward-delay: 4
      dhcp4: no
      dhcp6: no

dualnic-port-2.yaml

Code:

Code Select Expand

network:
  version: 2
  renderer: networkd
  ethernets:
    eth3:
      match:
        macaddress:  cc:cc:cc:cc:cc:cc
       
  bridges:
    br1:
      interfaces: [eth3]
      addresses: [192.168.4.2/24]
      mtu: 1500
      nameservers:
        addresses: [192.168.4.1]
        search: [localdomain]
      parameters:
        stp: true
        forward-delay: 4
      dhcp4: no
      dhcp6: no