An old router in a drawer is a small Linux computer with two or three antennas attached, and that’s more capable than it looks. Between open-source firmware and a handful of desktop apps that manage it, an unused router can become a smart-home network segment, a DNS-level ad blocker, a VPN endpoint, a backup access point, or a mesh node that closes a dead zone at the back of the house. The best apps for repurposing an old router as a smart home hub below cover every one of those jobs, mostly free, mostly open-source, mostly installable in an afternoon.
What to look for in a router-repurpose workflow
- Supported hardware. OpenWrt’s Table of Hardware is the reference; check your router before you download anything.
- Isolation for smart devices. IoT devices belong on a separate VLAN or SSID from your main network.
- DNS-level filtering. Blocks ads and known trackers at the network layer, works for every device.
- Remote access. Reach your smart home from outside via VPN or Tailscale-style mesh.
- Community activity. OpenWrt has weekly releases; some abandoned firmwares have not shipped a build in years.
- Backup and recovery. Bricking a router happens; a firmware with a serial-recovery path saves the day.
Quick comparison table
| App | Best for | Platforms | Free plan | Starting price | Rating |
|---|---|---|---|---|---|
| OpenWrt | Universal replacement firmware | Router firmware | Yes | Free | Excellent |
| DD-WRT | Enthusiast alternative firmware | Router firmware | Yes | Free | Very good |
| FreshTomato | Broadcom-optimised firmware | Router firmware | Yes | Free | Good |
| Home Assistant | Smart-home orchestration | Windows, macOS, Linux, HAOS | Yes | Free | Excellent |
| Pi-hole | Network-wide ad blocker | Linux, Docker | Yes | Free | Excellent |
| AdGuard Home | DNS-based blocker with UI | Windows, macOS, Linux | Yes | Free | Very good |
| Tailscale | Zero-config mesh VPN | Windows, macOS, Linux | Yes | $6/user/mo | Excellent |
The apps
1. OpenWrt
OpenWrt is the reason repurposing an old router is even a conversation. Weekly releases, thousands of supported devices, a package manager, and a web UI (LuCI) that turns the router into a general-purpose Linux appliance. Install it via the manufacturer’s firmware flash flow, then log in and start adding packages.
Where it falls short: Not every router is supported; the Table of Hardware is the reality check. Newer high-end routers can lag OpenWrt support by a year.
Pricing:
- Free: Full stack, GPL.
- Paid: None.
Platforms: Router firmware (installed via desktop browser).
Download: OpenWrt.org
Bottom line: The default replacement firmware for almost any router old enough to be gathering dust.
2. DD-WRT
DD-WRT is the enthusiast alternative to OpenWrt, especially strong on older Linksys and Netgear hardware. Cleaner web UI than early OpenWrt, though the modern OpenWrt LuCI catches up quickly. Good for routers that DD-WRT supports and OpenWrt does not.
Where it falls short: Release cadence has slowed compared to OpenWrt. Some builds are labelled “beta” for years.
Pricing:
- Free: Standard builds.
- Paid: None for community; commercial licences for OEMs.
Platforms: Router firmware.
Download: DD-WRT.com
Bottom line: For routers OpenWrt doesn’t cover, or users who bounced off LuCI in 2015 and want a friendlier UI.
3. FreshTomato
FreshTomato targets Broadcom-based routers (Asus, Netgear, Linksys) and squeezes strong performance out of hardware that OpenWrt sometimes struggles with. It’s a spiritual successor to the old TomatoUSB project.
Where it falls short: Broadcom-only, which limits the hardware pool. Smaller community than OpenWrt.
Pricing:
- Free: All builds.
- Paid: None.
Platforms: Router firmware.
Download: FreshTomato.org
Bottom line: Pick this if your old router is Broadcom-based and you want a stable, performance-tuned firmware.
4. Home Assistant
Home Assistant is the smart-home brain that sits alongside your repurposed router. Run it on a Raspberry Pi, mini PC, or the Home Assistant Green appliance. The router isolates IoT devices on their own SSID or VLAN, and Home Assistant orchestrates them without any cloud dependency.
Where it falls short: Learning curve is real; expect a weekend for the first serious setup. Some integrations require paid subscriptions to third parties.
Pricing:
- Free: Home Assistant OS or Container.
- Paid: Nabu Casa Cloud from $6.50/month for remote access convenience.
Platforms: Windows, macOS, Linux, or the HAOS appliance.
Download: Home-assistant.io
Bottom line: The smart-home orchestrator every serious setup ends up running.
5. Pi-hole
Pi-hole is the network-wide ad blocker that started the whole “run it on a Pi” wave. Point your router’s DHCP at Pi-hole as the DNS server, and every device on the network gets ad and tracker blocking for free.
Where it falls short: DNS-only, so it doesn’t block ads that ship in the same request as content. Setup requires editing your router’s DHCP settings.
Pricing:
- Free: All features.
- Paid: None.
Platforms: Linux, Docker, Raspberry Pi.
Download: Pi-hole.net
Bottom line: The default network-wide ad blocker; runs on the same box as Home Assistant if you want.
6. AdGuard Home
AdGuard Home covers similar ground to Pi-hole with a slicker UI and native DoH/DoT support. Runs on Windows and macOS as easily as Linux, which matters if you’re deploying on a repurposed laptop or NUC rather than a Pi.
Where it falls short: Overlap with Pi-hole means most users pick one, not both. Some feature parity is behind AdGuard’s paid tiers on the app side (Home is free).
Pricing:
- Free: All features.
- Paid: None for Home; commercial VPN and DNS as separate paid products.
Platforms: Windows, macOS, Linux.
Download: AdGuard.com/adguard-home
Bottom line: Pick this over Pi-hole if you’re running on Windows or macOS, or you want a nicer web UI.
7. Tailscale
Tailscale turns your repurposed router (or a Pi behind it) into a zero-config VPN exit node. Install the client, mark the router as a subnet router, and every device you’re logged in to reaches your home network as if it were on the LAN.
Where it falls short: Uses Tailscale’s control plane; if you want fully self-hosted, use Headscale instead. Free tier covers most personal use but caps device count.
Pricing:
- Free: Up to 100 devices, personal use.
- Paid: Team plans from $6/user/month.
Platforms: Windows, macOS, Linux.
Download: Tailscale.com
Bottom line: For remote access to your smart home without punching ports on the router.
How to pick the right one
Start with OpenWrt on the router itself. Add Pi-hole or AdGuard Home for DNS-level ad blocking (pick one). Layer Home Assistant on top for the smart-home orchestration. Add Tailscale for remote access without exposing ports. If your router isn’t OpenWrt-supported, try DD-WRT or FreshTomato based on the chipset.
FAQ
Can any old router run OpenWrt?
Not quite. OpenWrt supports thousands of routers, but not every make and model. The Table of Hardware is the definitive answer for your specific device.
Is it safe to install custom firmware on my router?
Generally yes if you follow the instructions for your exact model, and if the router has a recovery mode (most do). Bricking is uncommon on well-documented devices; unusual on any router less than ten years old.
What’s the smallest useful smart-home setup?
An OpenWrt-flashed router as the isolated IoT network, plus Home Assistant on a Raspberry Pi 4 or 5. Add Pi-hole on the same Pi. Total cost under $100 if the router is already in a drawer.
Do I need a smart home hub if I use Home Assistant?
Home Assistant is the hub. Individual protocol adapters (Zigbee dongle, Z-Wave stick, Matter bridge) plug into whatever hardware runs Home Assistant.
How do I isolate IoT devices from my main network?
On OpenWrt, add a new SSID bound to its own VLAN, then create a firewall zone that allows IoT-to-internet but blocks IoT-to-main-LAN. Most decent routers running OpenWrt support this in the LuCI web UI.
