I'm having an issue with this error code right now.. I have tried rebooting both the router and roku several times as well as changing out several ethernet cables.. I even factory reset the device and still get error 013.50 when trying to connect by ethernet.. I even logged into the router to check mac addresses from the dhcp and it only shows my laptop as connected.. before I reset the device, the last time it says that it checked for an update was in May,.. I new that was a lie because I checked in both July and August.. Is roku disabling ethernet as I have seen several other unsolved posts dealing with the same error. Is this something that should be reported to the FCC or FTC as a device that I use only used less than 10 times in the last year some how has ethernet bricked after I have had the device powered off for about 2 months??
Make sure the MAC address(es) shown under Settings->System->About aren't all zeroes. I think that error means it can't get an IP address from your DHCP server, but that's more of a guess than anything since Roku refuses to tell us what those error codes mean. Try "Network connection reset" under Settings->System->Advanced system settings. I don't know if it has any effect on wired connections, but it can't hurt.
Just out of curiosity, have you tried Wi-Fi?
I have both a mac addresses for both wired and wifi.. I can actually see the link lights on the ethernet port lit up on the roku and the router its attached to.. there is voltage on the ports.. the roku is connected through wifi, but that's not why I bought the ultra.. I bought it because it had ethernet as I didn't want to use wifi..
Wired should just work, but somehow Roku seems to have trouble at times. Have you tried a DHCP reservation on your router? I can recall having issues way in the past with a Roku refusing to accept a new IP address. You'd think the factory reset would have cleared everything, but you just never know with Roku.
I have CenturyLink, and was having this issue as well. I was able to connect for awhile when I factory reset, but found this post:
Basically enabling special characters worked