I  am fed up with  Eero tech support after  4 horrible experiences. My eternal gratitude in advance with anyone with the knowledge and patience  to help me.  Please buckle up and bear with me.

I have 4 Eero Pro 6E Routers,  a gigabit internet fios connection through a Nokia ONT ethernet port, and here is my strange  and perplexing story: Please refer  to these photos

1. In Closet 4 photo you see the 'big picture'. I am the first person to live in this  apartment, and this is what the wiring  closet in my apartment looked like when I moved in (without cables, equipment, etc) From day 1, the ethernet port of the ODN was turned off and if I connected anything  directly to the  ONT ethernet port there was no signal, no live internet connection
2. Until recently, the  source of my internet connection has been the left-most ethernet port in the row of ports above the ONT. In picture  4, the dark blue line is going  from the Eero to what  I call the 'Mystery WAN'.  I call it this because I have no idea where this jack is wired to or what the source of the internet connection is. I will get to this later, but recently a senior verizon tech who came to fix the Verizon gear said he had never seen anything like it and said I was not connected to Verizon (even though I had  been paying them)
3. So  for a year and a half, I was connecting to the internet through this mystery WAN, which speed tested as a gig connection but I have consistently had reliability issues with  my network which I first tried to deal with in many ways through changing mesh systems or otherwise through the wifi network.
4. I finally got fed  up and had Verizon  come and they activated the ethernet port on the ONT and I finally had  a live gig connection through Verizon and their equipment, or so I thought.  The Mystery Wan connection remained live but  I had no intention of using it.
5. I should probably describe the rest of my topology:
   1. The other 3 ethernet ports in the row, represented by the yellow lines in picture 4, are each directly connected to an ethernet port in 3 different parts of the apartment. 1 is wired to a port in the bedroom, 1 in the living room, and 1 in the office. They are all wired in the closet to the switch shown in the picture,  and I have an Eero Pro 6E router connected by ethernet to the ports that they connect to-the office, the bedroom, and the living room.  So I have wired backhaul for all non-gateway Eeros, and this is confirmed in the app as showing as wired connections with 1 gb capacity.
   2. So Each of those 3 routers have  one ethernet port connected to a port in the  wall, which connects directly to one of the ethernet ports in the row in the  closet. And each router has its other ethernet port connected to a switch which has several other  devices connected to it, so that as many devices as possible can have wired connections going all the way back to the WAN. I have over 100 devices on my network. I have also tested all the ports in that row in the closet and only 4 are live-3 go  to a room in the apartment and the 4th is the Mystery WAN connection
6. OK, so here is the incredibly perplexing problem:
   1. After Verizon activated the ethernet port and I began using their network, I realized there was a problem and attempted to troubleshoot it. The problem was when I ran a speed test using the verizon network, using either the Eero app or any speedtest I ran from my PC which is connected by ethernet to a switch in  my office which is in turn connected to one of the ethernet ports on my office Eero, I consistently get readings of 250-320 Mbps. Down and 900+ Up
   2. In attempting to understand and troubleshoot the dramatically lower speed I was getting, I did all of the following:
      1. The first thing I did to try and isolate the problem variable was very simple. All I did was remove the ethernet cable from the ethernet port in the Verizon ONT and, keeping the other end of the cable plugged into the Gateway Eero I then plugged the end that I had just removed from the ONT into the Mystery Wan port.  After waiting a few minutes for the network to reconstitute itself using the other WAN source, I ran the same speed tests on the Eero App and on my computer and I consistently got 900+ Mbps Down and Up
         1. At this point, I assumed the problem was with the Verizon connection, that I must just not be getting anywhere near the Download speeds I should be.   I also  assumed that there  was no problem with the Eero hardware or my topology, because everything worked perfectly and produced the expected performance by just unplugging the ethernet cable  from the Verizon equipment and plugging that same cable into the Mystery Wan port, changing NOTHING ELSE.
      2. To be certain, however, I then did a bit more troubleshooting:
         1. I hooked 2 different computers (one at a time)  up DIRECTLY to both the Verizon WAN via the ethernet  port  on the ONT, then unplugged it from Verizon and plugged it into the  Mystery  Wan port  HERE IS THE CRAZY PART: Each computer, when connected DIRECTLY to Either the Verizon WAN (Direct ethernet  connection from ethernet port on computer to ethernet port in Verizon ONT) or the Mystery WAN, very consistently produced 900+ Download and Upload speeds.
            1. So I am now unable to conclude that there is an inherent problem with my Verizon connection.  When I connect to it directly with either of 2 computers it consistently performs exactly  as it should.
      3. So I am left with the question of why I am getting terrible performance  using Eero on the Verizon network
         1. I know the Verizon connection is delivering what it is supposed to because  I have now tested it many times directly and it works flawlessly
         2. I know  the Eero equipment works and my network topology is sound because when I connect it to the Mystery Wan everything works flawlessly.  Literally the only thing that changes when I switch WAN sources is that I remove the cable from the Verizon equipment and plug it into the Mystery WAN. Nothing else changes. I don't even take the other end of the ethernet cable out of the port on the gateway So looking at picture 4, the only thing that changes going from Fios to Mystery Wan is the connection in green becomes the connection in Dark blue.  Note that the different  colors are not meant to suggest different physical cables but only a change in the signal path from the ethernet port of the gateway Eero.
      4. I had become friendly with the senior Verizon tech who activated the ethernet port on the ONT and he gave me his cell phone.  Even though Verizon, like all ISP's, has a policy of not supporting any 3rd  party equipment that is installed on a properly functioning internet connection, he came back to my apartment and I took him through the whole thing.  He could think of no possible explanation.  I was grateful that he came knowing that I had a functioning connection
         1. My tech support interactions with EERO, and there were 4 of them, were all incredibly frustrating and disappointing on so many levels.   In short, I spent a total of 16 hours over the course of 4 different calls and after painstakingly explaining all this each time, the support rep communicated via typing with a Level 1.5 tech rep (one level up) and in each case after being told all the facts the level 1.5 reps, who have the option to escalate further, each declined to do so and told me there was nothing they can do, it is not a problem with Eero, and my only recourse was to work with the ISP.   This was pretty much the most infuriating thing I could have been told, because of course the level 1.5 rep knows that every ISP has a hardcore policy of not at all  supporting third party hardware and only providing support if there is  a problem with the connection itself.
            1. This is fair because the ISP only commits to provide you a working connection- they can't be doing technical support for the myriad types of hardware that the customer chooses to add onto a working connection.
            2. Eero tech support totally passed the buck and not one of the 4 reps or the level 1.5 techs they consulted with acknowledged that the fact pattern seems to indicate that the problem has at least something to do with Eero, as the connection performs perfectly when Eero is taken out of the equation.  I should also say that each time I was told not only that I could not speak to the level 1.5 rep directly, but also the entire communication between the level 1 and level 1.5 rep took place via typing online with considerable delay between responses. 
            3.  I think this sytem is idiotic as it is incredibly frustrating for the  customer being left out of the loop and being made to wait for each response, without even knowing what is being said by either party. I cannot imagine why Eero would  not want to be sure that everyone  was on the same page and ensure that the problem I communicated to the level 1 rep was both well communicated to the level 1.5 rep and also understood by him or her.  The fact that each time I was told to go to the ISP, which is clearly  a ridiculous suggestion, makes me wonder whether any of the 1.5's understood the situation., In fact, given that such a complex problem was communicated second hand via a non-continuous text conversation, it would be a miracle if it was communicated and understood properly. I cannot imagine the rationale for this process- it is inefficient, ineffective, and leaves the customer feeling frustrated, helpless, unheard and disrespected. I have never experienced anything like it from another  company and it really soured my previous positive feelings about the company. 
            4.  I would think that they would want to escalate things like this as I doubt I am or will be the only one experiencing this problem and you would think they would want their engineers to be aware of edge cases so they can get in front of fixing them or documenting the solutions.  It seems to me that is the way a well-run company that cares about its customers and wants to inflict a minimum amount of pain and  frustration on them would operate, instead of what seems to be a codified  policy of passing the buck and pretending the problem has nothing to do with them
      5. So after wasting all that time with support, I am hoping that an Eero engineer or a brilliant and thoughtful community member can provide me the help that tech support made clear they had no interest in giving me.
      6. For those of you who might be wondering why I don't just use the Mystery Wan since it seems to work, the reason is that although the speed tests out, it still suffers from intermittent dropouts and slowdowns that have driven me crazy for upwards of a year It is such a shame because I love the Eero equipment- it works amazingly on the Mystery  Wan.  If I can just figure out why it is so drastically affecting the download performance of my FIOS account, I would be a very very happy camper. . .
      7. Anybody with the  patience to be reading this, you are a saint and have my sincere gratitude