From DD-WRT Wiki

 **NOTE**:  The A2 version can be flashed to DD-WRT after flashing v1.09 A1 stock firmware via Recovery Mode

[edit] Hardware Specifications

(D-Link DIR-868L rev A1 - Wireless Cat):

[edit] Installation Instructions

 **CAUTION**:  Do not upgrade through wireless connection unless the router is limited to only a wireless connection.
 **WARNING**:  Turning off power during the upgrade process may cause permanent damage to the device.
 **WARNING**:  TO AVOID BRICKING, DO NOT PERFORM A 30/30/30 VIA RESET BUTTON ON BROADCOM ARM ROUTERS
 **NOTE**:  SEE Where do I download firmware? for information on where to download firmware files.
 **NOTE**:  It is recommended to use a factory-to-ddwrt.bin firmware between 01-20-2015-r25974 and 05-28-2015-r27096
for initial flash. SEE: Known Issues
 **NOTE**:  builds since 06-05-2015-r27240 contain different folders for REV A1, B1, and C1 models.

Download the prescribed factory-to-ddwrt.bin and current release dir868[a|b|c]-webflash.bin

[edit] Flash from OEM factory firmware

1. Connect your PC via Ethernet cable to one of the LAN ports (Black) on the back of your router.
2. Launch/open a web browser and enter http://dlinkrouter.local or http://192.168.0.1 in the address bar.
• A login page will display. Default login is admin/no password. It is recommended to reset your router to defaults.
3. After you login to your router's user interface, click on the Tools tab at the top of the page.
• Click on Firmware from the menu on the left-hand side.
4. Scroll down the page. Under Firmware Upgrade, click on the Browse button and select the previously downloaded factory-to-ddwrt.bin file and click Open.
5. Click on Upload.

 **CAUTION**:  After you start the firmware update, do not try to go online, turn off the router, or do anything else to the router until it finishes restarting.

6. When the router has finished restarting, go to http://192.168.1.1 in your browser.
• You should be greeted by the password change page of the DD-WRT webUI.
7. Set username (optional, default username is root) and password (enter password twice, these *must* match and are case-sensitive).
• You should be greeted by the System Info page of the DD-WRT webUI
8. Click on Setup, then Wireless, then Basic Wireless Settings.
• You will be required to enter username and password previously set.
• You will want to set the regulatory domain under wireless settings and click Save at the bottom of the page.
9. Click on Administration, then Firmware Upgrade
   • Leave Do Not Reset selected for After Flashing
10. Click on Browse and select the appropriate previously downloaded dir868[rev a|b|c]-webflash.bin file specific to your router model version.
11. Click Open
12. Click Upgrade
• The firmware update starts and the router restarts. The firmware update process takes about five minutes.

 **CAUTION**:  After you start the firmware update, do not try to go online, turn off the router, or do anything else to the router until it finishes restarting.

13. If the webUI does not automatically go back to the Setup -> Basic Setup page, or does not stop at the progress bar page to allow you to click Continue after waiting at least five minutes (i.e. if you get a "Connection Reset" or other error page in your browser), enter http://192.168.1.1 (or whatever your router IP address is) manually or click and hold the "Back" button and select the appropriate history entry.
14. Click on Setup to begin configuration to your needs.
• You will be required to enter username and password previously set.
15. Click Save on each page (unless otherwise noted in a specific tutorial).
16. When finished, Click on Services or Administration tab and click Reboot.

• Note: The router doesn't support hard reset (30/30/30), select Reset to default in webUI or Erase NVRAM via command line instead.
• Note: The router's reset button works for resetting the DD-WRT settings, to do this, while DD-WRT is running, press and hold the reset button on the router's bottom for 15 seconds till the router reset and reboots. You will see the LEDs goes all off then the power LED starts flashing (indicates the router has went into recovery mode). Power off the router and power on again to access DD-WRT if recovery is not needed at the moment.

[edit] Upgrading (or Downgrading) DD-WRT

 **NOTE**:  Use the file named dir868[a|b|c]-webflash.bin.
 **WARNING**:  Do not use this file to go from Stock to DD-WRT.
 **NOTE**:  Reset to defaults is recommended if you are upgrading from a very old build (> 6 months).
 **NOTE**:  Do not restore a backup from one version to another version of DD-WRT, as nvram variable names may have changed.

1. Connect your computer to your router with an Ethernet cable.
2. Enter http://192.168.1.1 (or whatever you set your router IP to) into a web browser.
3. Enter username and password as required.
4. Go to Administration -> Firmware Upgrade
• Leave Do Not Reset selected for After Flashing
5. Click on Browse and select the appropriate previously downloaded dir868[a|b|c]-webflash.bin file specific to your router model version.
6. Click Open
7. Click Upgrade
• The firmware update starts and the router restarts. The firmware update process takes about five minutes.

 **CAUTION**:  After you start the firmware update, do not try to go online, turn off the router, or do anything else to the router until it finishes restarting.

8. If the webUI does not automatically go back to the Setup -> Basic Setup page, or does not stop at the progress bar page to allow you to click Continue after waiting at least five minutes (i.e. if you get a "Connection Reset" or other error page in your browser), enter http://192.168.1.1 (or whatever your router IP address is) manually or click and hold the "Back" button and select the appropriate history entry.

[edit] How to restore to factory firmware

1. Follow steps of Recovery Mode.
2. When returned to factory firmware, navigate to Tools - System and select Restore Factory Settings.

[edit] Recovery Mode

When the Power LED keeps blinking on boot, the router has entered the recovery mode. This usually happens when flashing a firmware went wrong, or the configuration has been corrupted.

It is also possible to (force) boot into recovery mode to restore a (soft-)bricked router or flashing back to the factory firmware:

1. Download the latest available firmware on the official D-Link website of the router revision.
2. Unplug all cables (incl. power cable) from the router.
3. Connect the router to the PC using one of the 4 switch ports.
4. Set the PC TCP/IPv4 address to 192.168.0.2 and use 255.255.255.0 as the Subnet mask.
5. Disable any running firewall(s), anti-virus, TCP/IPv6, etc.
6. Power-on the router with a paperclip pushing the hidden reset button located on the bottom of the device for a few seconds, when the Power LED starts blinking, release the reset button.
7. Open Mozilla FireFox (*other browsers doesn't seem to work correctly when trying to flash the firmware) and navigate to http://192.168.0.1.
8. Upload the stock firmware, when completed the router should report to reboot.
9. The router should now be running stock and accessible on the default address. (http://192.168.1.1).

[edit] Known Issues

• DO NOT USE builds 30432 till 34311 (also applies to DIR-880L): see tickets 5518 and 5963
• Except quarkysg mod builds, which also fixes Policy Based Routing with SFE accelerated NAT: issue 5900
• If flashing from the stock firmware to dd-wrt doesn't work, download a factory-to-ddwrt.bin firmware between 01-20-2015-r25974 and 05-28-2015-r27096. Afterwards try to upgrade to the latest dd-wrt build. REF: D-Link DIR-868L 5GHz missing, Dlink DIR-868L RevA1 can't load firmware

[edit] Bad WiFi drivers

• 5GHz band issue: this should be fixed in latest builds, however when the 5GHz band doesn't not pop up when you search for WiFi networks on your device or it will take a few seconds to show up (and disappear again), try to manually add the wireless network or change the Channel Width of the 5GHz interface to Wide HT40 instead of VHT80 (although this may affect performance).

[edit] OpenVPN

If using the inbuilt OpenVPN-server in tunnel-mode, you may need to use the following firewall rules:

iptables -A INPUT -i vlan2 -m state --state NEW -p udp --dport 1194 -j ACCEPT
iptables -A INPUT -i tun2 -j ACCEPT
iptables -A FORWARD -i tun2 -j ACCEPT
iptables -A FORWARD -i tun2 -o vlan2 -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i vlan2 -o tun2 -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o vlan2 -j MASQUERADE

• Note 1: Verify that the interfaces are correct by running the ifconfig command
• Note 2: You may need to adjust the above IP-address (& netmask)

The following Additional DNSMasq Options may also be needed, to stop DHCP(-service) on the tunnel-port:

interface=tun2 
no-dhcp-interface=tun2

[edit] D-Link DDNS

D-Link offers router owners a free dynamic DNS host name service (https://www.dlinkddns.com/). This service can also be enabled on the dd-wrt firmware:

A working state should give verification messages, like this one:

Thu Jan 22 23:11:21 2015: INADYN: Started 'INADYN Advanced version 1.96-ADV' - dynamic DNS updater. 
Thu Jan 22 23:11:21 2015: INADYN: IP read from cache file is 'x.x.x.x'. No update required.

[edit] Notes, Links, Further Reading

 **NOTE**:  There may be broken links within any of the threads below due to data loss or otherwise deleted content that we have no control over.

1. Restoring stock firmware D-Link DIR-868L
2. 5GHz Wireless Disconnects Clients Every 11.5 Hours
3. D'link DIR-868L Optimum, Need help with flashing.
4. DLink DIR-868L with optimum firmware
5. (DIR-868L | B1) - DNS problems
6. DIR-868 DD-WRT installation problem ?!? SOLVED
7. New build is out 27944 (BS) V3.0 - Several Routers Bricked!
8. (DIR-868L | B1) - How to fix port speed @ 100 Mbps
9. (DIR-868L | B1) - How to (re?)start Samba
10. D-Link DIR-868L Bootloop
11. DIR-868L Revison C1? (German Sub-Forum)
12. (DIR-868L) - Router freezes
13. (Solved) D-Link DIR-868L A1 stuck in Recovery Mode
14. (Fixed) Possibly bricked DIR-868L
15. DIR 868L bricked
16. How to Install DDWRT on DIR-868l B1
17. Dlink DIR-868L RevA1 can't load firmware
18. New Build 33345 for D-Link DIR-868L Rev A & DIR-880L Rev
19. Can't flash to D-LINK DIR-868L B1
20. Unbricking via Serial DIR-868L
21. New Build 33986 for DIR-868L & DIR-880L
22. New Build 34080: DIR-868L, DIR-880L, RT-AC68U (SFE w PBR)
23. D-Link DIR-868L - 16MB Flash Size? (DIR-868L A2?)
24. Starhub Dir-868L (DIR-868L A2?)
25. (SOLVED) Can't flash DD-WRT on D-Link 868L
26. D-Link DIR-868L 5GHz missing
27. D'link DIR-868L Optimum, Please Need help with flashing
28. Dlink DIR-868L Lost Credentials - Unable to log in
29. OPNSense VLAN Guest wifi with DIR-868L
30. DIR-868L Rev A with build r47182: Reboot will reset nvram
31. DIR-868L no 5GHz
32. D-Link DIR-868L : Could not find flash device 'nflash1.trx'
33. DIR-868L cannot get any sharing working
34. I can’t get my DIR 868L router to work
35. (DIR-868L) Huge "boot" MTD disables rootfs?
36. D-Link DIR-868L version A2
37. D-Link Forums > DIR-868L > Updating Firmware for version A2