Virgin Router and TP-Link AC1200 w OpenWRT

I'm trying to improve the stability and performance of my home network. For some time I've been using the Virgin router in modem-only mode and a TP-Link AC1900 as the wifi router. I have a small Synology NAS for a website and back up duties. The Virgin service is 110Mbps.

Although it's ok I still feel there could be improvement in the overall stability. Samsung TV and Virgin TIVO box seem to be particularly affected.

I've successfully flashed a spare AC1200 with the latest OpenWRT firmware but before I go any further I'm wondering if I'll see any benefit or should I be looking at replacing the Virgin router?

Sorry if this is a bit newbie but I am to this side of things!
Thanks in advance.