In Germany, for example, a Telekom-branded LH1000 is locked to Telekom’s network. If you switch to 1&1 or Vodafone, the router will refuse to connect. Unlocking removes the TR-069 remote configuration and the hard-coded VLAN IDs, allowing you to use the router with literally any ISP (DSL, Fiber, or Cable via Ethernet WAN).
There is no widespread OpenWrt or DD-WRT build for the LH1000. However, some users flash modified stock firmware from other Arcadyan variants (e.g., the "Green" or "Orange" branded versions). This is not recommended unless you have a UART-to-USB adapter and are comfortable bricking the device. arcadyan lh1000 unlock
There are three distinct reasons people search for "Arcadyan LH1000 unlock": In Germany, for example, a Telekom-branded LH1000 is