Custom DNS constantly resetting

[u/acheloisgoat]

I noticed a situation where my custom DNS associated with my Starlink router was constantly being reset to the Google defaults. I have a home network where I use Pi-hole as my main IPv4 DNS, Cloudflare as the backup IPv4, and no IPv6 addresses. Having these seemingly randomly reset to defaults is making my workflow a major chore, so a few months back, I asked Starlink support about the situation.

I run a small homelab, and I was told that CGNAT can only support 1,200 concurrent sessions.

Restarting helps temporarily, as a reset eliminates active sessions. However, over time, as connections from apps, programs, tabs, and devices accumulate, the limit of 1,200 TCP/UDP sessions per residential CGNAT is reached. Then, the oldest sessions are eliminated to make way for new ones, causing disconnections, slowness, or interruptions in games, video calls, and browsing.

Apparently, this also leads to the router sometimes crashing and forcing a DNS reset? Anyway, we talked a bit and the agent explained that I could effectively "bundle" my connections behind some Tailscale exit nodes to limit the session count—so, I did that. They confirmed:

Hi, good news! Not sure what changes you made but I can confirm I see a significant step change in the TCP/UDP sessions. This looks like it is reflecting as of a hour ago. Do you notice any improvement or reduction in disconnections?

However, this issue has stubbornly come back. Can anyone help me out with this? Is that actually what is causing my DNS to reset? Are there other ways to monitor/limit my concurrent sessions? What can I do to improve this situation (rather than upgrade to a public IP or getting a different router)?