Good day. A few months ago lost my internet connection and after no luck debugging the issue I simply swap my ISP ethernet cable from port 1 to 3

• Before swaping: Port 1 ISP. Port 2 Deco Secondary unit. Port 3 Switch
• After swaping. Port 1 Switch. Port 2 Deco Secondary unit. Port 3 Switch

Several weeks later there were some power outages due rain & wind. Internet and Deco units recovered but devices connected to switch were no longer accesible

• Removing the swicth and connecting the device (example. laptop) to port 1 didn't fix the issue (no switch issue)
• Ethernet cables working as intended (neither failure here)
• Attempt several scenarios (cant recall them) but ultimately only port 2 & 3 were working as intended

Upgrading to 1.2.6 didn't fix the issue and just yesterday I update to beta firmware 1.2.7 with promising results yet still issues

My results

• 2 XE75 Deco units
• Device and connection seems stable. No performance or disconnection issues so far
• Ethernet port 1 is empty, port 2 goes to a switch, port 3 goes to ISP
• Port 2 switch has on it: 1. Ethernet connection to Arlo hub station (security cameras), 2. Ethernet connection to network HDD, 3. Ethernet connection to another Deco XE75 unit

• Main Deco Working scenarios
  • Scenario 1: Port 1 empty. Port 2 switch. Port 3 ISP. Secondary Deco working as intended.
  • Scenario 2: Port 1 empty. Port 2 ISP. Port 3, switch. Seocndary Deco working as intended

• Main Deco NOT working scenarios
  • Scenario 3. Port 1 ISP. Port 2 switch. Port 3 empty (no IP, red light, no internet)
  • Scenario 4. Port 1 ISP. Port 2 empty. Port 3 switch (no IP, red light, no internet)
  • Scenario 5. Port 1 switch (w/o Deco unit). Port 2 ISP. Port 3 empty (there's internet, Secondary Deco works, but whatever is connected to the switch will be unaccessible)
  • Scenario 6. Port 1 switch (w/o Deco unit). Port 2 ISP. Port 3 Secondary Deco unit (There's internet, Secondary Deco works as well but devices connected to switch are unaccessible)
  • Scenario 7. Port 1 switch (w Deco unit). Port 2 ISP. Port 3 empty (There's internet at first, but after a few minutes the whole internet will stop working, including internet WiFi)
  • In brief
    • Whatever is connected to port 1 is NOT detected by Deco App
    • Whatever is connected to port 1 will not have internet
    • If there's another Deco unit connected to port 1 via a switch it will likely crash the Internet at all, including WiFi

After this, did swap Deco roles 

• Working scenarios (Main Deco, used to be Secondary)
  • Scenario 1: Port 1 empty. Port 2 switch. Port 3 ISP. Secondary Deco working as well
  • Scenario 2: Port 1 empty. Port 2 ISP. Port 3, switch. Secondary Deco working as well
  • Scenario 3. Port 1 ISP. Port 2 switch. Port 3 empty. Secondary Deco working as well
  • Scenario 4. Port 1 ISP. Port 2 empty. Port 3 switch. Secondary Deco working as well
  • Scenario 5. Port 1 switch. Port 2 ISP. Port 3 empty. Secondary Deco working as well
  • Scenario 6. Port 1 switch. Port 2 any device. Port 3 ISP. Secondary Deco working as well
  • Secondary Deco (old Main Deco) WORKS if connected via port 2 or 3

• NOT working scenarios
  • Old main deco (now secondary deco) NO working if connected via Ethernet port 1

Looks like Ethernet port 1 is my issue... Any way to figure out the root cause? Port no longer working? Really doesn't make sense that only 1 port is no longer working