It does not matter if you connect to the top or bottom connection RJ45 Ethernet connection. Try going into Settings, Internet, and look for an option to RESET NETWORK (or CONNECTION), any way, it will then actively seek the router and attempt to acquire/request an IP address from the router(DHCP). Very rarely (like 3 times a year) my H3 can't access the internet, so I go to diagnostics and force the H3 to RESET Internet Connection, which is initiating a DHCP, and then a few seconds later, I have access to the internet for download or streaming of VOD or the Apps.
Also, confirm the lights are on/blinking after you connect the cable. You can also try a different Cat cable (AKA, Ethernet cable) because maybe the one you are attempting to use is BROKEN. It is pretty easy to damage Cat cable and not know it. Once, I had a heck of at time trying to get a device to re-connect to the router, and while the Cat cable did NOT appear damaged from what I could see, I finally decided to try a new/fresh cable, and that SOLVED the problem. Cat cable must never be bent or under anything of any weight. It is VERY easy to break Cat cable even if it appears to have never been bent nor mistreated, but sometimes it is too tightly wound for storage. Best of luck.