Arris NVG599 Passthrough Setup for Eero Pro 6E

That's very much in line with your line stats.  It very much looks like your line is not an issue.  Leaving us with the PC to the eero, or the eero to the Gateway to deal with.

Yes, that's correct about the nearly 1 gig file and about 4 mins left.

From Smart Home Manager

I'm wondering if maybe I ought to delete the Eero-created network and restart that part from scratch. it is possible that I did the eero setup without the Arris fully in Passthrough mode....and maybe it didn't set something correctly, even though Eero said that it did.

Also, do I need to setup the Eero to use PPPoE and with or without a login? There is an option for that in the App

No, you do not need PPPoE.   It looks like things are set up properly, though it's really hard to tell for sure.  Can you test your speeds when directly connected to the base eero by Ethernet?

Yes, on the computer that is directly hooked-up to the Eero's ethernet port with an Ethernet cable from the Eero to the computer's NIC card, the speed is the same:   25 mbps. when downloading files.  In other words, that computer is not using wi-fi at all.  This is the Eero that is wired to the NVG 599's LAN port 1.

Okay, what happens when that same cable is connected directly to the Gateway itself (once it has released its eero IP and gotten one from the Gateway)?  Still same speed?

I'll try the connection in a bit.  One question, should I be connecting the Eero to the WAN port on the NVG 599?  Or to the LAN port?

EERO WAN port to any one of the four NVG 599 LAN ports.