Connectivity problem

Assume the attached infrastructure. From C and D I can go anywhere, however from A and B it's like I couldn't see beyond the DD-WRT, in fact, I can't ping the DD-WRT. This is a "problem" because when A and B want to use the printer, they have to switch to the AP of the DD-WRT.Before I had the same setup, but the other way around (and other ISP router), ISP router was at the right and DD-WRT at the left, and both were linked by wifi using the Repeater Bridge mode, and there wasn't any problem at all. I can't use this setup anymore due to the switch from ADSL to fiber.Right now I'm out of ideas, really can't figure out what is the problem. Checking DD-WRT's documentation, Linking Routers - DD-WRT Wiki, everything seems fine.

diagram.jpg

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Priston

Can C and D reach A and B? If so, can A and B reach C and D? If they can they should be able to reach the printer...

How is DD-WRT connected to ISP router? using the lan port or wan port?

Deathmage

If that ISP router really is a router it should have those addresses in its routing table and since it's all the same network it shouldn't matter.

But for shits and giggles do you have a normal 5 port switch laying around, plug the LAN cable from the ISP into it and some of your devices and ping between them and see if you can access the internet too. If you can the DD-WRT isn't translating your IP range correctly or perhaps it's has conflicting traffic if it still thinks its the network router....

yzT

hey! just recovering back this thread as my mother reminded me of this problem.. xD

Nowadays, the DD-WRT has been replaced for a TP-Link which I don't remember the version, one of the latest with Gigabit ports and wifi AC, yet the problem is there.

I have disabled firewalls, NAT, etc, but anything seems to work. Another test I did, if I connect the printer to the ISP router, then C and D can't print. What's odd is, why is the gateway is the ISP router, both computers have access to Internet and however they can't connect to another device attached to the gateway?

elTorito

Mind sharing the brand and model of this "ISP router"? Reading through your whole story, this is the device that seems to be the biggest question mark. Without knowing what kind of device this is, and what its capabilities are, it's hard to make any suggestions.

Also, since you call it the ISP router, do you have access to its management console or GUI? If that's the case, perhaps there's a diagnostic function that enables you to ping (using the router's internal interface/192.168.1.1) other devices in your LAN, directly. This rules out some exotic isolation function on the ISP router being the culprit.

Also, your diagram says that the ISP router is functioning as a DHCP server. What is "A" then? Does A have an IP address of its own (on the 192.168.1.0/24 subnet)? Can A ping B and the other way around?

Finally, why are you connecting devices to the ISP router anyway? Seems to me that all devices directly connected to the DD-WRT/TP-Link are communicating with each other and the WAN just fine, so why insist on using the ISP router as an access device? I'm missing some important clue here

OctalDump

I wouldn't set it up this way. Put the wired stuff all on one switch, and hang the WAP off the same switch. Ensure that the WAP isn't doing routing/firewall/DHCP/NAT or any of that nonsense.

My gut feeling is that the wireless access is the problem, and is likely to do with its possibility to be used as a router. Another option is to bridge from the ISP router to the TP-Link and use the TP-Link as the router for the whole network.

yzT

@elTorito ISP's is a Comtrend VG-8050 with ISP's rebranded software. "A" is just a laptop connected via DHCP, while the others have a static IP. There is no diagnostic tool for that, just for testing if a device is attached to any of the ethernet ports.

@OctalDump actually all wired PCs are attached to the same router, the TP-Link. Then the TP-Link is connected to the Comtrend via cable as well. Also tried to allow a bridge from TP-Link's AP to Comtrend, but it doesn't work either.

The TP-Link has the following routing table:

destination network 192.168.1.0, subnet 255.255.255.0, gateway 0.0.0.0, interface LAN & WLAN.

Should I change something about it?

PS: just checked the TP-Link is Archer C2 (C750).

OctalDump

Are you using the "internet" port on the TP-Link? Probably, that's the first thing to try if you are. Since the gateway is on the same subnet, it should be on the "LAN" ports.

Also check the TPlink config for any gateway like services eg NAT, routing, DHCP. Ideally, turn off routing if you can.

Priston

Priston wrote: »

How is DD-WRT connected to ISP router? using the lan port or wan port?

This...

elTorito

Like OctalDump said, check the operating mode of your TP-Link (AP, AP/Router, Repeater). The way you've got things set up, the ISP router should just take care of the routing. Your TP-Link doesn't even need the 192.168.1.0/24 route in its table, since you've got a flat network anyway.

yzT

It's connected to a LAN port. About the operating mode, I don't see anything relevant.

varelg

yzT wrote: »

@elTorito ISP's is a Comtrend VG-8050 with ISP's rebranded software. "A" is just a laptop connected via DHCP, while the others have a static IP.

This. Have you reserved static IP addresses with the DHCP on the network? Also, it seems you have two DHCP servers in the same network, I hope you expect some conflicts.

yzT

No, I don't hace two DHCP servers. DHCP is disabled in the TP-Link

varelg

Can you then reserve a static IP address for the tp-link? And then make the tp-link to be gateway for your computers connected to it?

OctalDump

yzT wrote: »

It's connected to a LAN port. About the operating mode, I don't see anything relevant.

I suspect that the TPLink won't let you turn off routing. It's a common problem with all in one devices that you can't easily just use a subset of features - and the gateway features (route/NAT) seem to be the hardest to turn off.

So, you could get a vanilla switch and a dedicated Wireless Access Point (sometimes called Wireless Bridge). Alternatively, if you can bridge the connection from the ISP provided router to the TP-Link so that the TP-Link has the WAN address on its WAN port, that would be a good option, too.