When you say you "enabled roku development mode", did that step actually work, i.e. did you get the Roku Developer Settings screen to appear on your TV, along with the address of your Roku, "http://192.168.3.110", and "Username: rokudev", and then selected the button labelled, "Enable installer and restart", and then notice your Roku re-boot. If you're not sure, try that step again. Make sure it says Enable installer and NOT Disable installer, if you press the button when it says Disable installer, then you'll be undoing what's already been done.
Are your system that you're using to run the web browser and your Roku on the same subnet? Depending on what type of router you have, the router should have a settings page, e.g. DHCP settings, which specified the address ranges of devices on the network. If your computer's IP address is 192.168.2.25, you should see a subnet mask of something like 255.255.0.0. Also, check what subnet your computer thinks it's on, e.g. on Windows, from a Command Prompt, type: ipconfig
What are you typing in your web browser to attempt to communicate with your Roku? http://192.168.3.110 and what happens when you do that? Does the request time out or do you get to the "Authentication Required" prompt?
Try another means of communication, e.g from your computer's console, type: ping 192.168.3.110, and see if you get back a reply.
After all this, try re-booting the Roku again then accessing a couple of channels, then go back to the Roku home screen and try your web browser again.
What model of Roku do you have?
