RV340W - Some Computers Connected to LAN but not Internet

[devon12345678]

I am running an RV340W for a SMB networking application. I have about 20 computers connected to this router via ethernet and a handful of switches. Right now, most computers are working completely fine while some are able to connect to the network but unable to connect to internet.

All of the computers are on static IP addresses.

When I check the TCP/IPv4 properties on one of the problem computers, everything matches the DHCP Server I set up in the RV340W router. The IP address is within the Range Start and Range End. The DNS server is set to dns-server-static and the Static DNS1 and DNS2 match what is in the TCP/IPv4 properties.  

My DHCP Server is set to 192.168.3.1-192.168.3.255. I have a problem computer at 192.168.3.126 but a good computer at 192.168.3.132

When I check the VLAN settings in the RV340W, I don't see much I could change other than the Mask or the Inter-VLAN Routing. 

Any ideas on what else I could check to see what's going on?

[Flavio Miranda]

Hi

 Just clarify one thing, please:

"

ll of the computers are on static IP addresses.

When I check the TCP/IPv4 properties on one of the problem computers, everything matches the DHCP Server I set up in the RV340W router."

So, which one you are using? Static or DHCP?

For DHCP which is the mask you used?

From the PC, does you can ping the default gateway?

For the DHCP server, in case you are using it, you can not allow the whole network range:

192.168.3.1-192.168.3.255

You need to exclude at least one IP for the gateway and yo dont use the last IP .255 if you mask is 255.255.255.0.

[devon12345678]

Let me reword what I said.

All of the computers are on static IP addresses.

All of the computers are set to use pre-specified IP addresses and DNS Servers in the TCP/IPv4 Settings. See image attached. 

Mask is set to 24. IPv4 Address is 192.168.3.1. Subnet Mask is 255.255.255.0

I can ping the default gateway from both bad and good computers.

I changed the range to 192.168.3.2-192.168.3.254. 

[Flavio Miranda]

From a networking perspective,  if you ping the gateway, you could access anything allowed by this gateway 

 From one troble machine, if you ping

www.google.com 

And ping 8.8.8.8

The result is both fail?

[devon12345678]

Correct. If I ping google.com and 8.8.8.8 from the bad computers they both fail.

From a good computer on the same network I can ping google.com and 8.8.8.8. 

I discovered something new - the internet on the bad computers is intermittent. They will manage to connect to the internet every now and then. I'm convinced somehow the IP addresses are conflicting so some are getting kicked off while others are not.

[devon12345678]

Additional discovery - if I change the TCP/IPv4 settings on a bad computer to obtain IP address automatically, it is able to access both the LAN network AND the internet. 

I don't know why I don't have to do that for the good computers. I also prefer to set a pre-determined IP address so I can save that IP address for remote access purposes so I'll still like to find the actual root of this problem. 

[Flavio Miranda]

But how are you doing this? Are you using excluded ip address?

For example, did you reserve from 192.168.3.2 up to 192.168.2.240 for DHCP

and then, for those machine you dont want DHCP, you use from 192.168.3.241 up to 192.168.3.254 ?

If not, try to do this. Surelly this is some conflict.

[devon12345678]

Unfortunately that did not work.

Does the attached trace mean anything to you? The successful and failed ping were taken minutes apart from one another.

[devon12345678]

Cisco deleted a reply I had from earlier:

I changed the range to 192.168.3.26-192.168.3.120 and reset the router to free up all the DHCP IP addresses. Still having the same problem with the same computers. LAN connection, no internet connection.

Two interesting things I've found:

1. When everyone has left the building, I was able to get a bad computer to connect to the internet, even when I set the IP address. It there a maximum number of users the router will deliver internet to?

2. When I set a bad computer to obtain the IP address automatically, it is somehow obtaining an address outside of my range. So even though my range is 26-120, somehow this computer obtained 192.168.3.151. It is possible for computers to be assigned an IP address from a different source than the Cisco RV240W router? This might be the source of the conflict and the intermittent internet connections.

[Flavio Miranda]

Very interesting.

1. When everyone has left the building, I was able to get a bad computer to connect to the internet, even when I set the IP address. It there a maximum number of users the router will deliver internet to?

Yeah, it is possible.  Take a look on the NAT configuration. NAT uses a ACL to match the traffic of interest, if this ACL has mask wrongly configured, it may limit the number of IP that can go to the internet.

2. When I set a bad computer to obtain the IP address automatically, it is somehow obtaining an address outside of my range. So even though my range is 26-120, somehow this computer obtained 192.168.3.151. It is possible for computers to be assigned an IP address from a different source than the Cisco RV240W router? This might be the source of the conflict and the intermittent internet connections.

You can have mode then one scope on the DHCP server. But, you probably would see it.  Chech different devices. I see you have a netgear and more switches. And the ISP also may offer IP.

[devon12345678]

I haven't been able to look into the NAT configuration yet but I continued chasing the idea that computers on the network are obtaining IP addresses outside of the DHCP server range. I discovered that our network currently have two WANs. Can't get an answer from the person who originally set it up but I don't think this is necessary. One is set to DHCP, perhaps that is the rogue DHCP server?

 

[Flavio Miranda]

Could be but it seems that it is down.  But, yes, can be something like that.  What you can do is change you internal IP range completely, so, if you have any rogue DHCP server on the network, will be more clear for you.

 You can use a range like 172.16.0.0/24 or 192.168.4.0/24 or even 10.x.x.x/24. 

[devon12345678]

The NAT configuration page is completely blank. I don't think it's in use. Would it be helpful to create a NAT? Or should I start trying to follow a new lead?

[Flavio Miranda]

If you dont have NAT you can keep this way. As this router is not directly connected to the internet, the ISP routers is doing the NAT for you.

[devon12345678]

OK. If it's not NAT, are there any other Firewall settings I can dig into to see what's causing this?