There isn't any beta available at this time. They updated the same v1.03 file in Feb of this year and did not graduate the v1.0# for some reason.
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So I recommend doing the following if you can get logged in or you can reset the router so you can log in correctly to the routers web page;
1. Re-download the v1.03 from the main web site and unpack it on the PC.
2. Factory reset the 645 using the routers web page Tools/System if you can get there using IE only. DO NOT USE any other browser for this event. FF is ok.
3. After the router resets and comes back to ready, log in and skip any set up wizards.
4. Send the .bin file that was unpacked under Tools/Firmware. Let the router process the FW file and come back to ready.
5. After the router is back to ready,
do one more factory reset using the routers web page under Tools/System.
6. Let the router reset and come back to ready.
7. Set up the router from scratch.
Do not load any saved configuration file from the previous version that was saved. It shouldn't allow you to do this anyways. I noticed this when I updated my 645 to v1.03. Just set it up from scratch.
Let us know how it goes.