Fixing network at bosses house. router won't connnect to internet from modem, but will if I use the switch before the router

Nov 2, 2018
I'm having a ton of issues trying to figure this out. This is a new house so everything is new.Our ISP is BTES from bristol TN Its a fiber service, Modem is mounted outside with 2 lans, 1 lan is going into the power box,.

The modem has a cat 5 cable running into the basement, This is connected to a megabit Ethernet switch. Then this branches out to a router then. I'm reading you don't want a switch before the router because it can't route traffic.

So I re wired everything and connected the router straight to the outdoor modem using a cat 6. When I do it this way the light turns orange and the router will not connect to the internet. But If I use a cat 5 cable and connect it to the switch the modems light turns green. I can then run a cable from the switch to thr router and get the internet to work this way. Issue is, whatever the switch sends traffic to first will get priority. SO the wired pc ( what I'm typing this from) will get full speed, about 80 mbits. But anything connected to the router will get like 25kbs. That isn't the only issue. We have a wireless printer that needs to talk to the router to talk to the pc, but this won't work with the current setup. Because the pc is connected to the switch, but the switch is connected to the router witch would connect to the printer. I can' talk to anything beyond the switch. It's just a basic 10/100 switch, does not route anything.

I'm not sure what the issue is. I have this same internet at my house, connected to the same router and it works fine. I've cut the switch from the equation, but it will not work. If I connect the router straight to the the modem using a cat 6 it won't work, no internet and orange light. But a cat 5 connected to a 10/100 switch gets a green light. I am beyond confused. I've tried resetting everything. Releasing and renewing ip, this doesn't work. I'm not sure if its the cat 6 cable. But it works if I connect it straight to the switch then this pc. So the cable works.

I don't know, but some guadance would be great. I can't seem to make any progress.

If I need to give more information, just ask. I'm running outta ideas on how to track this issue down.
There are many layer 2 encapsulation types. It's possible the router doesn't have the one the modem uses, but the switch has both.

Can you check your router to see if it's WAN interface is set to receive it's address via DHCP? on one of the devices that's working check it's ip address. If the router is configured as a bridge you might have a public one. factory restting the router might help.

It doesn't cost much to upgrade to 1Gbs stuff. I would suggest buying a new 1Gbs router and seeing if it works. If any of the equipment is old it's worth replacing.