is the remote access control feature enabled on the 825? I presume it is.
Can you install a remote access program on a local always ON PC like teamviewer and connect there and see if you can access the routers page there?
There is no SSH way to remote in to the router from behind the web UI or FTP.
Only reason that the UI might be hung up is that router itself is hung up and that is caused by a configuration issue or a problem on the LAN or WAN side.
Also swap out cables between the ISP modem and 825. CAT 6 is recommended.
Also if your ISP modem supports Gb WAN port speeds, change the 825s WAN port speed from Auto to 1000Mb
There is newer FW available. You could try to update using this:
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forums.dlink.com/index.p ··· =42457.0However I recommend reviewing this and trying some of the tips and suggestions before updating FW:
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forums.dlink.com/index.p ··· =54498.0