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Umm how did you aquire the eero? was it brought or part of an isp deal/pushed upon you/upgrade?
also is it on the latest firmware ? the eero needs to be on v6.61 (dec 2001 release) for pppoe support
They were bought as a triple back direct from Amazon about a year ago.
On the official Eero app they are identifying as "Eero Pro 6" and all running v7.1.1-16
It's very odd. And I am sure when I first set them up, PPPoE was definitely an option but I went straight for bridge mode.
I haven't resorted to a factory reset yet though ( not even sure that's an option )