Okay, that's interesting. Many times, the modem will identify itself with a particular device, most commonly a router or switch (most routers are also switches). If your ISP does this, then you can't switch out devices easily. A switch or wireless router connected to a modem prevents this problem.
Now, this may not be what's going on. Can you connect a different device to your Ethernet cable that's running from your modem? Say, a laptop?
If a different device can be used without issue, then this is not what's going on. However, if no other device can connect properly using the Ethernet cable from the modem, then this may be the issue. If so, you'll need to work with your ISP about this. And, if this is the issue, I'd suggest getting an inexpensive switch (around $20), or an inexpensive wireless router (with switch, around $35).
Roku Community Streaming Expert
Note: I am not a Roku employee.
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I have the exact same problem. I can connect wireless, but the signal is weak which is why I wanted the wired connection.
I have rebooted the router and rebooted the roku box but I still get the message it cannot detect the eithernet cable.
I have used several different ethernet cables, and I can connect my PC to the same ethernet cable and it works fine.
When I look in the ethernet port on the Roku UltraLT, the connection wires are way in the back and look like they are too short. My ethernet cables click in and are secure.
@sjjanson, if no lights come on by the Ethernet jack when you plug in the cable then the Ethernet port may just be bad or the cable isn't making a good connection.
I am having the same problem with Roku Express 4K+. It amazes me that you all about the more expensive product and it still doesn't work. I am disgusted by the copy pasta Dannybot. I was so pleased when I found that Roku tested adapters and approved them to allow their device to be plugged into an Ethernet. I am disappointed and disgusted by their refusal to deal with this flaw in their product.
They should not sell a product if they are not willing to support it. Obviously
Connect to your network: http://192.168.0.1
LAN SETTINGS > DHCP Settings
Fnd the "DHCP name special character state" setting, then choose to “Allow Special Characters” and reboot.
THIS JUST WORKED FOR ME!!!
WORKED! My new Ultra 4800R was not connecting to the router via Ethernet or wireless. I have a **bleep** Centurylink Gig-Fiber Calix C844G modem/router, firmware: CCO004-11.1.600.8.
Lo and behold... down in Advanced settings/DHCP Settings/DHCP Name Characters: "Allow Special Characters"!!!!
Gold star KingJoe29
I have 3 Roku Ultras. I have a wired connection to all 3 Ultras. They have all been working fine since Nov.7 2021. All of a sudden one of them stopped working on the wired connection. I have checked the cable and it reads though from end to end. I also changed ports on my router hub. I have tried restarting both the Roku and the router. The only thing I can think of now is the ethernet port on the Roku has gone bad.
Thanks for the post.
For troubleshooting purposes, have you tried switching out the ethernet cable to see if you are still experiencing the same issue?
Please keep us posted what you find out.
Add me to the list of Roku ultras that was working on a wired network for a month and it just decided to stop working. Lucky I can get wireless to work decently or this would be a complete bust. I will not buy another Roku if this is the quality I’m getting. I was a happy customer until the product failed after a month.
I just opened up a new ROKU ULTRA and my wired internet connection is totally flakey!! Yes, I have switched ethernet cables, yes, I have rebooted my router, it still does not stay connected! Any other device I plug in works just fine. Roku tech support is horrible - plus, there's no phone number to call so you're at the mercy of someone in chat that takes 5 minutes to reply to each question. Planning to return this unit and but another Firestick...