Confusing Networking Problem with Asus RT-AC87U Router

[dmills913]

Hi, I'm a low-intermediate ability networking guy forced to be my company's network administrator. I have a tricky problem that MAY just be a simple settings issue.

Network:
ISP Modem -> ISP Router (4 port, non-wireless)
Port 1 -> ASUS RT-AC87U (4 port)

ASUS RT-AC87U
The ports on the Asus router are plugged into Netgear switches (GS108v3) and then into computers, 2 printers, 2 rokus, and 5 internet security cameras.

The network was running fine on a ZyWall USG20W router, but the router kept dying, so I bought the ASUS.

After buying the ASUS, and just doing the simple set-up, two of the computers on port 1 had internet, 1 didn't, and none of the other computers on the network did. Wireless worked fine for some devices (iPhones and iPads) and didn't for any android devices. It worked fine on two laptops, but not on the third.

Neither of the Rokus nor any of the internet security cameras can get internet at all.

Plugging a roku directly into the router from the ISP gives internet just fine.

When automatically obtaining a DNS from the router, some computers are fine (generally the ones on port 1) and other computers will alternate between normal and throwing a "dns probe finished no internet" error.

On all of the computers, I can give them internet by going around the Asus DNS and setting specific IP, Subnet Mask and Default Gateways as well as specifying a DNS server (either google or Open DNS).

When looking at the internet on the Roku, it says that it has a connection to "Your wired network" and "Your Local Network" but not to "The Internet".

From all I can tell, this has to be a problem with the ASUS Router connecting to the WAN. But, some computers are fine.

Any advice on where to check next?

 

[kanewolf]

I would think you would want to toggle the operations mode on the Asus from router to AP mode. You are in a double NAT situation if you have it configured as a router.

 

[dmills913]

Ok, that's interesting. So, just to confirm, even though I need the Asus to provide wireless (and I want to use the USB 3 for NAS), it should still be set up as an AP?

 

[kanewolf]

Ok, that's interesting. So, just to confirm, even though I need the Asus to provide wireless (and I want to use the USB 3 for NAS), it should still be set up as an AP?

Definitely for wireless. I am not sure about USB, but I would try it.

 

[dmills913]

Hi, I'm back at the office now. I set up the router as an AP, but it didn't fix the problem. The first computer to initiate contact with the point got internet, but all of the other computers complained of having the same IP address. This leads me to believe that the other router is set up as a pass-through rather than NAT (if I'm using the terminology correctly).

So, back to square one.

After putting the ASUS back in wireless router mode and doing a full reset, all of the computers complain of not having a valid IP configuration. I believe the problem is the ASUS connecting to the DNS server? I tried changing the asus settings to let it obtain automatically from the ISP, and also tried setting it to 8.8.8.8 and opendns as well. Neither one changed anything.

Again, I can give any computer on the network internet by assigning an IP, subnet mask, default gateway and DNS server, but that doesn't help for devices that I can't set manually like that.

Any other thoughts?

 

[kanewolf]

Hi, I'm back at the office now. I set up the router as an AP, but it didn't fix the problem. The first computer to initiate contact with the point got internet, but all of the other computers complained of having the same IP address. This leads me to believe that the other router is set up as a pass-through rather than NAT (if I'm using the terminology correctly).

So, back to square one.

After putting the ASUS back in wireless router mode and doing a full reset, all of the computers complain of not having a valid IP configuration. I believe the problem is the ASUS connecting to the DNS server? I tried changing the asus settings to let it obtain automatically from the ISP, and also tried setting it to 8.8.8.8 and opendns as well. Neither one changed anything.

Again, I can give any computer on the network internet by assigning an IP, subnet mask, default gateway and DNS server, but that doesn't help for devices that I can't set manually like that.

Any other thoughts?

First question, Is the ISP router necessary? It doesn't sound like it isn't doing anything.

 

[dmills913]

That was sort of the route I was considering next. I can probably dig up the paperwork on the pppoe settings from the ISP and plug them into the asus router. The only thing that it's doing is using Port 2 for our main phone line (also through the ISP, and I hope that that line doesn't require it to be plugged into the ISP router...). I liked having them separate because resetting the router wouldn't cut out our business phones. (Also, I'd need to buy another switch due to losing 3 ports hehe)

It's not the end of the world, and I may have to go that route if there isn't a better option. I was sort of considering it anyway. It's just weird though, as the old ZyWall router never had problems in wireless router mode (until 6 months ago when it started randomly shutting off).

Thanks for the help. I'll try taking the ISP router out of the loop and seeing if everything runs better. It'd certainly be one less layer of complexity to take it out.

 

[dmills913]

Well, I've spent the last hour hooking and re-hooking up the network back and forth with and without the ISP router in the loop. No matter what I try, it won't give me internet without their router in the loop, even trying to mimic every setting they have in their router inside the ASUS.

I know it's possible to get this working somehow since the old router was fine with it. I appreciate the advice you've given so far. Any other thoughts?

 

[dmills913]

SOLVED:

In the end, I unplugged every device from every switch, and started plugging things back in one-by-one. Things worked fine until I got to one of the internet security cameras. Something about it went wrong, and every time it was plugged in, it took down the whole network. Plugged in everything except that one camera and everything is fine!

Only took me the better part of two weeks to figure it out...

tl;dr Unplugged and plugged in everything one-by-one. One device was causing the entire problem.