I have a Linksys WRT1200AC that I've been running with OpenWRT for about a year and a half now. The last time I made any changes to my router was in spring of this year when I upgraded to OpenWrt 19.07.1 from OpenWrt 18.06.5. I only mention that to point out that I haven't made changes in about 6 months or maybe longer.
IPv6 with prefix delegation has been working fine on this router for that whole time, until recently. I noticed that IPv6 connectivity stopped working on my desktop PC under both Linux and Windows, and I noticed that the PC wasn't being assigned a public IPv6 address.
So, I checked the router, and noticed that it appears I'm no longer getting an IPv6 prefix delegation from DHCPv6 from my ISP, Spectrum Cable, which I had been in the past. Screenshot below (slightly redacted to obscure most but not all of my public IPv6 address for the router itself, the IPv6 gateway of my ISP, and the mac address of my router's WAN6 interface). Note that it doesn't show any delegated prefix. I swear this box used to show a delegated prefix, but no longer does.
Here is the configuration for the WAN6 interface (from Luci):
So what I want to know, is there any logging either already enabled, or that I can turn on to increase the logging, to capture the DHCPv6 request & response (from the upstream DHCPv6 server), that can be used to prove that Spectrum's DHCPv6 isn't working right?
I need to hand them something that proves that the problem isn't the configuration of my router (or maybe it is, and the log will show me that, and that's helpful too), but that my router isn't getting a proper prefix delegation from DHCPv6.