I also have the same problem with the Eero 6 Pro.  I have 4 of them; 2 connected via Ethernet port, and 2 of them via WiFi mesh.  When the Spectrum Internet goes out, ALL of the Eero's have red LEDs, and there is no local LAN persistence, so everything on WiFi disconnects (the Eeros haven't been power cycled).    The local LAN (WiFi) should remain up when the Internet goes down.  Also, when the Internet does come back online the Eero's can take up to 30 minutes before they return online, and often need to be power cycled to restore the WiFi.  This is unacceptable.

Eero support: how can the Eero 6 Pros be configured to maintain their LAN persistence and not turn red/drop WiFi whenever the Internet goes down??

3 year old topic, apparently still doesn't work. My eero and client will not transmit a wifi signal if the internet is down. eero server is connected to my DSL modem and LAN with Cat 6 cable. No reason why WIFI and local LAN access should be down even though I cannot get WAN access. You are selling Wifi systems rather than internet repeaters, aren't you?

Well I had it.  Returned my four (4) EERO Pro 6 units to Best Buy and spent the extra to buy the 3 pack of the NETGEAR - Orbi AXE11000 Quad-Band WiFi 6E Mesh System.  Yes, its costly, but they claim it will keep up the local internal house network even when the outside provider goes down.  These units have a fourth wireless band they use to talk to each of their units.  Now I just realized I need to test this new setup so I'll have to come back and report.

What finally killed the EERO is I simulated a down internet provider by disconnecting my cable modem.  For a short time all my units were flashing a white LED color and the "intranet" local network still functioned.  I could access my NAS downstairs from my office upstairs via the EERO network.  Then after sometime passed, all four of my EERO units went solid RED and my local "intranet" network went down.  I could no longer access my NAS, Home Assistant smart home was down, the "home" network was down.  This should NOT ever happen.  Local Wi-Fi should never be contingent on having an external "internet" connection.

Ok, so hopefully later today I'll be able to try a simulated down internet connection with my new Orbi units and report back.  First, I have many body parts to cross, a few prayers and offerings to the network gods, as well as breakfast and walking the dogs to get done...

I just spoke with EERO support. The call went to their third level support, where I was informed that LAN Persistence is only supported in Routed mode, not Bridged mode.  Therefore, if you lose Internet connectivity and you use EERO Bridge mode (as most IT professionals will do), your WiFi network is no longer going to work (it's more complicated, but keeping it short... some traffic will get through making it the issue that much more frustrating to identify).  I have 7 EERO Pros and I have evangelized how awesome EERO is to industry peers (I am a Network Solutions Architect) but now I feel so foolish for having done so ... I've already started to clear it up with folks I have made recommendations to, and to find a wireless solution that can stand on it's own.  Apparently it's been a known issue with EERO for many years and remains unaddressed. I loved EERO until I figured this out. Hopefully I can find a suitable alternative that performs as well but without the limitations.