Thank you for your help so far. Just to let you all know where I am up to, here is an update.
After a hectic week when I was unable to take the link off line, I grabbed an old CISCO 2600 router and threw a base config on it to test. With this config, I was able to achieve a ping on the second IP address.
ip address dhcp
encapsulation dot1Q 1 native
ip address 188.8.131.52 255.255.254.0
no snmp trap link-status
Looking at the CISCO config, it is using a default VLAN to achieve the link using the "Framed Route". So I have added a VLAN on my WAN interface on the RB2011 with the VLAN set to 1. I can now ping that address from the internet.
0 R ;;; WAN-NBN
ether1-AussieBB-WAN ether 1500 1598 4074
[Cut out irrelevant interfaces]
16 R ;;; DMZ
bridge-DMZ-SW2 bridge 1500 1598
17 R ;;; INT
bridge-INT-SW1 bridge 1500 1598
18 R vlan1 vlan 1500 1594
ip address p
Flags: X - disabled, I - invalid, D - dynamic
# ADDRESS NETWORK INTERFACE
0 ;;; DMZ
192.168.10.1/24 192.168.10.0 ether8-DMZ
1 ;;; INT
192.168.11.1/24 192.168.11.0 ether2-INT
2 184.108.40.206/23 220.127.116.11 vlan1
3 D 18.104.22.168/23 22.214.171.124 ether1-AussieBB-WAN
From the internet site https://ping.eu/ping/
--- PING 126.96.36.199 (188.8.131.52) 56(84) bytes of data. ---
64 bytes from 184.108.40.206: icmp_seq=1 ttl=53 time=290 ms
64 bytes from 220.127.116.11: icmp_seq=2 ttl=53 time=276 ms
64 bytes from 18.104.22.168: icmp_seq=3 ttl=53 time=282 ms
64 bytes from 22.214.171.124: icmp_seq=4 ttl=53 time=290 ms
I will now work on the outbound routing from the VLAN interface.