@David-TP 

i have same issue

  @David-TP Thank you for this information and I'm sorry it has taken so long to respond.  I have disconnected the Ethernet backhaul and both the middle and bottom ports are working on the satellite now.  I have configured the main deco with the Synology on the middle port and that is working.  However, the firmware has been updated to 1.2.8 in the meantime as well (Build 20230901 Rel. 36505).  Is there a reason to use the middle port on the main and the bottom port on the satellite?  Is there a correct way to hook up the Ethernet backhauls on the satellites?  It is looking like Ethernet backhaul from main Deco to first satellite does not work on top port of satellite and needs center port.

@David-TP Hello, the third satellite is not connecting via Ethernet backhaul to the second satellite.  It is working wirelessly but signal is 2/3 bars, would really like to Ethernet connect for the best performance.

  @Breaktackle Same issue.

Top port - sporadic, slow 50 down, 30 up, some packet loss. Doesn't show activity on switch.

- changed cables. same

- firmware is up to date.

- used port 2 to connect to switch. activity light worked, traffic was at max speed 500/500

Oddly, after about 2 hours, same slow speeds showed up for devices

I'm at a loss right now. Is there a better admin portal for the router?

  @Breaktackle and @David-TP

I just had this happen to my mesh yesterday. The top port on my main unit just stopped working. I installed newest firmware and reboot, no help.

My temporary work around is the switch that was plugged into the top (now dead) port, is now daisy chained into the switch that is plugged into the middle port, so those devices are working again.  
 

Seems odd that these units are all failing at once like this?

  @Akra5ia Is that just wireless traffic or both?  I had some slowdowns over WiFi that I traced to the channel width.  I'm speculating if the access points are close enough together there could be some interference overlap.  Reducing the channel width eliminated this issue wirelessly but if it's wired I feel like there could be a firmware issue with the ports.

  @Breaktackle Wired and Wireless. 

I ended up swapping my "Garage" AP with the "Main" AP that was having the port issue. Did the recommended steps from a comment above. All three ports of the "Garage" unit work. I renamed them for convienience but it all worked and took about 5 minutes to do the swap. Now both the wired and wireless are showing similar speeds. Rough 500/500 down/up. 

I have no idea why all of us are experiencing this at relativlely the same time. it wasn't from a firmware update, at least not an immediate result of the firmware update. I can't see any details of the ports or manage them via the Deco app or the website so I am in the dark on what the error is. It was super strange for me. I wasn't showing a link status on my switch for port 1 but I was still getting traffic at the slow speeds with packet loss (30/7 down/up). I replaced cables which didn't do anything. When I changed from the top port to the middle port, link status came up and the speeds were fine.

Now that I have swapped units, it is working as expected but I am not holding my breath because whatever caused the port to fail in the first place, could happen again to the AP I replaced Main with. We shall see.