Intranet (operating on LAMP server RPI) inaccessible on outside immediate local network

I am currently configuring an intranet for my farm; to allow me to input and track some data between my storage yard, cattle yard and house.

I am running into an issue which i'm sure has to do with my router, however I lack the requisite knowledge to correct and i'm hoping someone can either assist me with troubleshooting the problem, or assist with repairing the problem with some instructions.

Context, issue and ancillary is as below:

1. My network consists of a router, a switch and another router connected to a wireless repeater to broadcast internet to my storage and cattle yard.
2. There are approximately 11 devices (computers / laptops) located within the immediate network, which has the network location of 192.66.66.XXX, including my LAMP RPI, all of which are connected to the switch.
3. All these computers are connected via ethernet, and all can access the intranet on my internal domain (intranet.local) and the IP address 192.66.66.XYZ.
4. My storage yard and cattle yard are situated approximately 200m and 400m; respectively, away from my main residence and receive internet; albeit awful internet, from the wireless repeater, and they can access external websites without an issue.
5. It appears that when using the wireless repeater, it assigns all devices on this network a new network IP, being 192.168.10.X, despite being connected to the same router.
6. I assume that this acts in essence as its own "switch" and effectively means the two terminals located in these buildings are on a different local area network.
7. I dont know how to get this to sit on the same network as my other devices.
8. nor do I know how to configure my router to expose the 192.168.10.X network to my other local network without exposing my port 80 to the rest of the world.
9. If its not obvious, I clearly did not set up this network and I spend most of my time trying to avoid screwing anything too serious up.

If someone has any knowledge on how I could potentially bridge these networks, or what I am required to do on my router that would be fantastic.