routing – Adding a default gateway to linux does not take affect and it just uses the

I have a server and a firewall in a cloud environment, the details are as follows,
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with the following details for each component,

server c6:b0:c0:a8:e8:06
firewall c6:b0:c0:a8:e8:03
default gateway 00:03:ba:da:0c:b7

As this is based in the cloud, I do not have any control of the default gateway and cannot make any changes to it. I would like to route external traffic through the firewall by setting the default gateway on the server as the firewall’s IP. I did this by running the following command,

ip route add default via

I have confirmed this has worked by running the following commands,

ip route get

The results are as follows,

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However, when I initiate traffic from to an external host, I do not see the traffic hitting the firewall. There is no firewall/network rules in between the firewall and the server.

I have checked my arp table and it is as you would expect,
enter image description here

When I run the following command and run a packet capture,

telnet 8089

I get the following results,

enter image description here

The packets are leaving the server and heading towards the firewalls MAC, but I do not see the packets arrive (I have run a packet capture on the firewall and nothing)

Why Would this be? What can I investigate further from the host ?