Exactly
Try TP-Link routers which supports Wireless AC standard. This is the best cost-effective solution.
A problem arises if your SLT router doesn’t support AC standard though.

As in my personal setup, I use a dedicated AP just to distribute my main internet connection wirelessly. As per my experience, default main routers doesn’t do a good job sharing the internet. If you’ve got the money, use two new APs at both ends

otherwise, just use one
Edit: I’m not sure about costs, I’ve bought mine online. TPlink archer series.
Before buying a router model, always check the model number in WRT forums if it’s supported. Good luck