Hello. Im a idiot who is trying to install wrt on the aforementioned device. I flashed it using this mt7621-dlink_dir-878-a1-squashfs-factory.bin. The router seems to work, DHCP work with IP 192.168.1.1 but page doesn't load. I did factory reset and going to recovery mode with no result. Did I brick it?
Given that the D-Link DIR-878 A1 has only been supported since july, only master/ snapshot builds are available at this time. These snapshot build however don't include luci (the webinterface) and only allow access via ssh (from where you can install luci), in other words everything appears to function as documented and you haven't bricked anything, just connect via ssh and install luci.
No option for GUI at all? I mean the classing web access?
Sure, but you first have to install it via ssh.
I have the DIR-878, and I used to build my own pre-baked version of OpenWRT, making some things easier, though longer to build on the front end. I recently had my first experience with the snapshot, and since it required a full re-install (I backed up what I needed, but it wiped my config on install), and so had to manually setup some stuff before I could finish the install and restore...
With that said, one more thing with using the snapshot is that you need to manually configure the WAN network using the UCI system. Start with the following link, mainly the "\etc\config\network" section. If you can manually configure the external connection to the internet, installing LUCI and finishing things up with a GUI is much easier for some.