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I have wifi but cannot use LAN cables

By Reagan S · 8 replies
Jun 30, 2018
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  1. My father was an IT/ networking master. He died last week and I'm trying to figure out why some of his computers and routers do not have internet. We DO have wifi (although not as fast as usual). I traced all LAN cables down to one huge networking box that has one cable going to the first router. When I unplug this LAN cable the whole house loses all internet including wifi. When I hard wire into this router with a LAN cable coming from 1 of the 4 ports I do not have internet access therefore none of the computers, switches, or other routers that are connected via these LAN cables have internet. But again the wifi works from this router. I didn't know this could even be possible. All internet searches bring up the opposite problem (wired internet but no wifi). Please help me I am not a completely useless person when it comes to this stuff but compared to my dad I felt like.
  2. jobeard

    jobeard TS Ambassador Posts: 12,493   +1,430

    On systems running Windows 10, we frequently need to update the Local Area adapter.

    Also, it's always a good idea to power cycle the router(s) all of them, starting with the one connecting to the ISP
  3. Gabriel Pike

    Gabriel Pike TS Booster Posts: 145   +33

    It is possible that he may have VLANS running from router to AP. I have something like that setup in my home. We would need more information to help you. Do you have access to any of the devices?
  4. Mark Fuller

    Mark Fuller TS Booster Posts: 199   +6

    Where is the lan port the ethernet cables are plugged into? If it is plugged into a switch you might try plugging it into a different port or since your wifi router gets you online you might plug the cable into one of the lan ports on the router. Also, if a switch is involved you might bring up the command line interface of the switch and see if the port is shut and open it.
    Last edited: Jul 2, 2018
  5. jobeard

    jobeard TS Ambassador Posts: 12,493   +1,430

    Common consumer switches have no CLI - - not even configurable.
  6. Mark Fuller

    Mark Fuller TS Booster Posts: 199   +6

    He said that his father was an IT master and from what he said he might have more than a common consumer switch. He needs to further define what he means by his huge networking box.
  7. Reagan S

    Reagan S TS Rookie Topic Starter

    I'm sorry there was such a huge delay. I had to get back to my parents house and take a few moments to look at this more. Ok...

    My dad's wired network consists of the cable going into a SMC networks D3G0804W (seems like this is a router and modem in 1), then 1 LAN cable comes out into a D-link router, there are 4 LAN cables coming out of that. 1- into a computer, 2- into a switch, 3- into another router upstairs (very long cable), 4- into a network attached storage server. Obviously there are many more LAN cables coming from the switch (in fact into another switch) and from the other routers but those are the first 4.

    I reset the d-link router and set up the passwords and networks. This did not slove my problem. I also reset the SCM modem but again this did not change the connections except for 1 bit. Before when I would use the LAN cable from the modem into the laptop it wouldn't connect to the internet (but it will give wifi through the router???). After resetting the modem when I hardwire to the laptop it wants a network security key. Since none of the equipment is supplied by the cable company (charter spectrum) I do not know where to find this. But again when I just use that same LAN into the router the wifi works (although poorly) but none of the wired in connections.

    As I'm typing this it seems like I may need to figure out how log into the SMC gateway (if it is a modem and router in 1) and look at those setting.

    I appreciate the patience with me considering I'm not at their house every day, there are a million things involved in getting his estate ready, and I am a IT/networking beginner.
  8. jobeard

    jobeard TS Ambassador Posts: 12,493   +1,430

    The is a docsis 3.0 cable modem
  9. Mark Fuller

    Mark Fuller TS Booster Posts: 199   +6

    This device is configurable and seems to be made for older operating systems like vista, xp and even 2000 according to the operator's manual you can look up on line. The best advice I could derive for you would be to reboot the device(one of the tricks of the trade is to unplug the modem and wait three minutes and plug it back in, this clears the memory of the device which may be a problem) or reset it to factory defaults(it will probably need to be reconfigured if you do the latter). Also, how many pc's are connected to the system and what are their operating systems and what internet browsers do you use? I think the only browsers that are supported today go beyond what vista is capable of and surely xp and 2000 unless you use Mozilla firefox which I heard is capable of getting these os's online although I don't know for sure. There are instructions in the manual for disabling proxy settings which will make a pc not get online if it is enabled, although I don't think that is your problem from what you say if some of your pc's can use wi fi . Your best bet is to reboot the device or reset to factory defaults. There are instructions in the manual to login and configure the router (http://www.eastarkansasvideo.com/assets/d3g0804w-user-manual.pdf). You will need adobe reader to download it. A bit of bad news is that it has terrible reviews on amazon. It was posted on amazon on April 1, 2015, so it is indeed an older device. The ultimate best bet would be to junk it and get a new one or call your ISP and see what he can do for you. If this device is provided by your ISP you should ask for a newer model and have them configure it for you since they are responsible for it.
    Last edited: Jul 12, 2018

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