Remotely access drop in mode network

I have a neat thing that I figured out how to fix remotely and wanted to share.
20x with cat18 module, two cellular internets and 1 wired wan.
MSP Fortinet router.
ISP Cable modem.

Goal: Install peplink in drop-in-mode

I was waiting for an ISP to give me a /29 block of public ip’s.
I preinstalled the peplink in front of my my MSPs router.
ISP → Peplink WAN, set as dhcp
Peplink LAN 1 to my MSPs fortinet ISP ,set as dhcp.
The next day , while on another site.
Once they gave the ips the MSP changed the ip on his Fortinet , and saved.
However it didn’t give him a chance to save the gateway under their sdwan settings.
Now we have the public ip on the peplink, the peplink in drop in mode and the new public ip the MSP wants to use on their fortinet.
However , the fortinet still has no gateway set…
So remotely I did a layer2 tunnel from peplink at customers to my peplink and assigned my laptop a static ip in the range of the wan ip block set on the fortinet
then I was able to get in and access and setup the gateway on the fortinet. All remotely!!
Since Layer2 works as if you are local on the network , it doesn’t matter that the gateways on each device did not match.
Then I just removed the layer2 vpn tunnels, and now the peplink and the fortinet both have the correct ips.

Need crazy solutions to complex problems, send me a message, let me know.
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