15m is not too far for Wifi. If it is too far from your router you can use a WiFi extender.
I use a Google Mesh Wifi system to cover my entire house and garden. I have one downstairs next to my router that is connected to it via an Ethernet cable. It covers the downstairs rooms. Another one upstairs covers the top floor of the house and the garden. I don't use the Wifi on the talktalk router because many that come from ISPs have poor range and are buggy in my experience. I just use the supplied router as a an ADSL modem and use the Google system as my router and Wifi. It does mean that for my VPN server I need to port forward twice, once on each router.
