Did you try to change the SSID of your network? It's possible the IP-address of the router is somehow stored with the network data in the TV. Changing the SSID is - in effect - the same as selling the TV to somebody else who connects it to his own existing wireless network. That should be supported by the TV, somehow.
Another option might be to reset the TV to factory conditions, somehow. Then even your SSID is considered new. But I would wait with that until someone more knowledgeable with this TV joins the discussion.
I have posted this in the Samsung manufacturer's forum, but not sure if that's the right place so i'm posting it here as well....
I have this strange problem connecting my Samsung tv to my network. Let me state the facts...
A. TV is a Samsung LCD C750 2010 model.
B. I am using the Samsung wi-fi dedicated dongle
C. My modem/router (2 in 1) is a Thomson Technicolor TG582n
1. With repeater switched off, the TV can see the wireless network, but the signal is very very low. Still, when it manages to catch the signal, I run the network test on the TV and the 4 steps run successfully. Internet apps work, however they soon fail due to very low signal.
2. I recently bought an Xbox, placed just next to the TV, and it simply wouldn't detect the signal... so I bought an Edimax EW-7416APn which I have configured as a Universal Repeater.
3. The Xbox now works perfectly fine, and indeed all my other wireless devices like laptops, mobiles etc.. are working perfectly with the new Edimax repeater - the strongest possible signal, full networking and internet functionality.
4. Then I thought, now that I have a repeater, why not try connecting the TV again through it. So I browse for networks, find my homenetwork in the list (showing an excellent signal, now that it is being detected from the repeater), select it, and enter the pass phrase.
5. I run a network test on the TV and:
MAC Address test: passes
IP/DNS test: passes
Gateway ping: FAILS
The TV has acquired an IP, so there is communication with the repeater and indeed with the router which has provided the TV with an IP address. I can even ping that IP address from my laptop (which is connected via cable directly to the router) - so definitely, there is some kind of communication between the TV and the router and the TV is indeed on the network. However, I've tried millions of combinations and the network test simply fails on the Gateway Ping.
I have tried with/without security, changing channels and a number of other settings, but to no avail. I have tried manual settings on the TV... setting a fixed IP just outside my DHCP range (192.168.1.251), subnet mask 255.255.255.0, and gateway and DNS server IPs to those of my router (192.168.1.254).
Since the TV connects fine (when it manages to do so due to weak signal) to my router, I tend to point my finger at my Edimax repeater.
However, since all other devices are happily connected to the repeater, I then tend to point my finger at the TV!
Or perhaps at the combination of both!
Any idea what I else I could try?
P.S. using cable is out of the question and moving the modem/router to bring it closer to the TV is out of the question too, due to my home layout.