Only one wireless connection allowed Internet

Question

I have a TP-LINK TL-WR940N router connected to a cable modem. I have two computers connected via WLAN one of which is a laptop using a 802.11a/b/g/Draft-N card and a PC using TP-LINK TL-WN722N (150Mpbs) external Wireless card.

I have set up DHCP address reservation for these computers assigning them IP addresses from 192.168.0.100 to 192.168.0.102.

My wireless settings use channel 1, 11bg mixed mode on 54Mbps (I have tried various other configurations).

My laptop can connect to the router but has no Internet access, while the PC has Internet access. I got the laptop connection working a few times. However, it wasn't clear what was the issue and I couldn't add new devices to the network. My PC always has connection and all devices can connect to the router, but only the PC can connect to Internet.

I have not NAT setting on the router and I am not using MAC cloning.

Does anyone have a suggestion or a solution?

Edit 1

I have tried resetting the router to factory settings. The whole problem started after I updated the device's firmware. The network was functioning well before the update (I am certain that the firmware was of the correct version).

I also tried ruling out certain things. I have tested the router with the setting for 11g only and I am getting varying results: the laptop had a connection after the setting change, but now has lost it again. The PC has constant connection.

Edit 2

The router is 192.168.0.1. DHCP is configured to assign addresses from 192.168.0.100 to 192.168.0.199 range.

Each computer connected wirelessly to the router can ping the other (all computers in the network can ping one another).

Solution

The firmware was fine. However, the resetting of the router after installation of the new firmware erased the DNS cache. For some reason, it seems that the ISP's DNS server wasn't functioning. My PC was configured to use 8.8.8.8 and 8.8.4.4 (Google DNS), so it wasn't affected by this. I set the router to use Google DNS and the problem was fixed for all computers.

I discovered the solution when I tried to ping Google by its IP address from the laptop.

Comments

[Ramhound]

What intranet address does your router have? If I were to hazard a guess it would be 192.168.0.100 this means your network can only ever assign two intranet address. This by design?

[Igor Ševo]

The router is 192.168.0.1. DHCP is configured to assign addresses from 192.168.0.100 to 192.168.0.199 range.

[Igor Ševo]

Any number of devices should be allowed. The problem is not in establishing connection to the router. The problem is to establish a connection to the Internet. I have LAN for any number of computer in the WLAN network. However, only one of them has Internet access.

[Ƭᴇcʜιᴇ007]

Are you using the router as the DNS server for the clients, or something else? Can devices on the same router ping each other by IP? Can you ping Internet sites by IP from any/all devices? Did you try flashing back to the old firmware yet? If you do a tracert from a malfunctioning device to an Internet site, how far does it make it?

[Ramhound]

You need to update your question to reflect the network configuration ( your first comment ) I glazed over that comment since it should be in the question not a comment.

[Igor Ševo]

Tried that. All of this happened after updating the firmware (I am sure it is the correct version of firmware).

[Kinnectus]

Can you DOWNgrade the firmware back again? - You could even try re-flashing the firmware with the latest one just in case something went wrong that isn't showing yet?