I have many nerdy friends who have been Linux users for ages. But most of them don't know such a thing as Openwrt exists or have never bothered to give it a try.
It's a very fun piece of software to play with and can be extremely useful for routing traffic.
Wondering why it isn't more popular/widely used.
I do know about it, but I don't even have internet at home.
Though I do use DD-WRT on my WRT160NL which I use at school. For me it acts as firewall + setup-free VPN + DNS Ad blocker (NextDNS). I also have separate passwordless guest network on it if someone wants to use my router. Separate subnet, unbridged with net isolation and AP isolation enabled. And also QoS set to "Bulk" while my network is set to "Maximum". And also forced DNS redirection enabled, so that everyone who doesn't use DoT or DoH uses NextDNS.
You really want to either update to a supported release or stop using it entirely. It is very insecure to run network equipment with known security issues