I'm not experienced with this stuff. My parents have this configuration (attached) in their house for their fibre internet. It was set up like this back in 2015 and it's located in their garage. Meanwhile, the "main" wireless modem/router is in the middle of the house in the office. Back when it was setup, they used to have a landline phone plugged in as well.

When it was installed I think it was described as an access point or something. Truth is, there are times the internet has dropped out because this box is playing up, and we'd like to get rid of Huawei devices from our network. They've just got a Netgear Orbi and they're switching internet providers. 

I don't really know enough about this. Is this Huawei box actually doing anything important or is it literally just routing to another point in our house? Could we get rid of it and just plug a cable in so the router in the office does the work, or is that just not how it works at all? Likewise, is there anything more elegant we can get to replace the Huawei box, and if so, what exactly? I've tried Googling but I don't even know what to search without getting nothing but ads for new routers.