I have 2 Pack Deco M4 and I'm experiencing slow speed on 2nd unit. My modem and the Main deco have the same speed of 50 Mbps but when I'm connected to 2nd unit, I'm only getting less than 1 Mbps speed.

Setup:
Modem -> LAN Cable -> Main Deco - LAN Cable -> Satellite Deco (2nd).

So far I did the following:

I tried to switch the Main Deco and 2nd unit and I was able to isolate that the unit 2 is the problem. When the 2nd unit wasthe Main Deco, I'm experiencing the slowness.

The two (2) Deco has the same Firmware 1.4.3 Build 20200918 Rel. 74289. I already tried different setup and reset the unit multiple times but still no luck. 

Do you think that the second unit has hardware problem?