We got Spectrum installed in the last two weeks. After a few days I started to fall off the internet and required me to reboot all the appliances to get back on, not good. I had techs come out three times and they got things going and it appeared okay, but later the issue kept happening. Later my son came over and turned off all the IPv6 on the router config and got rid of the internal DNS pointing in the router and now we point out directly to another DNS. Not only are we up and running but at must faster speeds than before. My son who works for Cisco says that sometimes IPv4 and IPv6 do not play nice together. I am no network tech but I was about to throw Spectrum out and go back to ATT where I had zero connection issues. I see a lot of other issues reported here on folks having the same dropping issues and I think you need to educate your techs on how to fix it. Those of us who work from home cannot deal with this.
By removing the IP addresses for Spectrum's dual stack IPv4 / IPv6 DNS servers from your router, you now force every name request to traverse the Spectrum's internet transport layer to one of a handful of IXP locations, where it then will be rerouted to the alternate external 3rd party DNS server site you selected. I don't see how that change is going to improve your general download speeds, but maybe your son (the Cisco kid?) can explain it.
These forums, going back a few years to the pre-merger TWC days, have been very aware of the problems that develop when both IPv4 and IPv6 are used on the same network. The technical responders on this forum commonly remind folks that turning OFF IPv6 in their home routers generally resolves the conflicts between IPv6 and IPv4. And Spectrum's internal redundant DNS servers are all equipped with dual stack IPv6 + IPv4 response capability.
To this day I'm not aware of any subscriber on Spectrum's home internet service running hardware that operates only on IPv6 and cannot support IPv4 addressing, or needs more device addresses on their home LAN than IPv4 can support. Rest assured that Spectrum is not running out of IPv4 addresses for home users just yet!