Key takeaways
- Strong 5 GHz range for its time. The 4×4 Quantenna radio gave it better coverage at distance than most 3×3 routers of its generation.
- Early MU-MIMO hardware. It was among the first routers advertised with multi-user MIMO support, though few client devices took advantage of it.
- ASUSWRT features. Adaptive QoS, a VPN server, guest networks, USB file and printer sharing and detailed traffic controls.
- USB 3.0 port for network storage, still handy for basic file sharing.
The ASUS AC2400 router, best known as the RT-AC87U, was a fast Wi-Fi 5 flagship when it launched in 2014, but in 2026 it is not worth buying: its age means slow Wi-Fi compared with today’s models, no Wi-Fi 6 or 7 support, gigabit-only ports and a firmware support window that has closed. If you already own one and it is stable, it can keep running as a secondary access point; if you are shopping, an entry Wi-Fi 6 or Wi-Fi 7 ASUS router is faster, safer and often cheaper.
This review covers what the AC2400 class offered, how it compares to current routers in numbers, its known weaknesses, and what to buy instead. If your box says AC2400 but shows a different model number, check the label under the router; the advice on Wi-Fi 5 limits still applies.
RT-AC87U key specs
| Spec | ASUS RT-AC87U (AC2400) |
|---|---|
| Wi-Fi standard | Wi-Fi 5 (802.11ac), dual band |
| Max link rate | 600 Mbps (2.4 GHz) + 1,734 Mbps (5 GHz) |
| Antennas / streams | 4 external antennas, 4×4 MIMO on 5 GHz |
| 5 GHz chipset | Quantenna 4×4 radio (separate from main SoC) |
| Processor | Broadcom dual-core 1 GHz |
| Memory | 256 MB RAM, 128 MB flash |
| Wired ports | 4 x gigabit LAN, 1 x gigabit WAN |
| USB | 1 x USB 3.0, 1 x USB 2.0 |
| Launch year | 2014 |
The “AC2400” label is the sum of the two maximum link rates (600 + 1,734, rounded). No single device ever sees that speed; a typical 2×2 laptop connects at up to 867 Mbps on 5 GHz.
What it did well
- Strong 5 GHz range for its time. The 4×4 Quantenna radio gave it better coverage at distance than most 3×3 routers of its generation.
- Early MU-MIMO hardware. It was among the first routers advertised with multi-user MIMO support, though few client devices took advantage of it.
- ASUSWRT features. Adaptive QoS, a VPN server, guest networks, USB file and printer sharing and detailed traffic controls.
- USB 3.0 port for network storage, still handy for basic file sharing.
Known weaknesses
- Heat. It runs warm, and owners commonly reported instability when it sat in enclosed cabinets.
- 5 GHz radio quirks. Because the Quantenna 5 GHz chip is a separate module, it had a reputation for 5 GHz dropouts or the band disappearing until a reboot on some units and firmware versions.
- Limited third-party firmware. The closed Quantenna driver limited what community firmware projects could do with it.
- End of updates. It is well beyond its support life. A router that no longer receives security patches is a real risk on an internet-facing connection.
How it compares to current routers
| Feature | RT-AC87U (Wi-Fi 5, AC2400) | Typical Wi-Fi 6 AX3000 router | Typical dual-band Wi-Fi 7 router |
|---|---|---|---|
| Max 5 GHz link for a 2×2 phone/laptop | 867 Mbps | 2,402 Mbps (160 MHz) | 2,882 Mbps (160 MHz, 4K-QAM) |
| Realistic speed at 10–15 ft | About 400–600 Mbps | About 700–1,200 Mbps | About 900–1,800 Mbps |
| Many-device efficiency (OFDMA) | No | Yes | Yes, plus Multi-Link Operation |
| WPA3 security | No | Yes | Yes |
| WAN port | 1 Gbps | 1 Gbps (2.5G on some) | 2.5 Gbps or faster on most |
| Security updates in 2026 | No | Yes on most current models | Yes |
| Typical price new | Not sold new; used units are cheap | About $90–$200 | About $150–$350 |
Real-world speeds are approximate and depend on client devices, walls and interference. The gap that matters most is not peak speed but efficiency: Wi-Fi 6 and 7 handle 30 or more connected devices far better than Wi-Fi 5.
Is the RT-AC87U still usable in 2026?
| Your situation | Verdict |
|---|---|
| Main router on a plan under 300 Mbps, few devices | It works, but the lack of security updates is the main reason to replace it |
| Gigabit or multi-gig internet | Replace: Wi-Fi 5 and gigabit ports cap what you can use |
| Many smart home devices or a busy family network | Replace: no OFDMA, older CPU |
| Spare router to use as a wired access point behind a newer router | Reasonable, if kept on its final firmware and with remote admin off |
| Buying a used one | Skip; a new entry-level Wi-Fi 6 router costs little more |
If you keep it: practical tips
- Install the final official firmware from the ASUS support page for your exact model.
- Disable WPS, UPnP if you do not need it, and remote web access from the WAN.
- Change the admin username and password from the defaults.
- Give it open air for cooling, ideally standing upright on a shelf, not in a closed cabinet.
- If the 5 GHz band drops, set a fixed channel (36 to 48 or 149 to 161) and an 80 MHz width instead of Auto.
- Consider running it in access point mode behind a newer, supported router so the newer device faces the internet.
What to buy instead
Budget replacement
An ASUS Wi-Fi 6 router such as the RT-AX58U (AX3000) covers most apartments and small homes, supports WPA3 and keeps the familiar ASUSWRT interface with AiMesh support. Wi-Fi 6 models like this are often discounted now that Wi-Fi 7 is the current standard.
Current-generation choice
For gigabit or faster service, a Wi-Fi 7 ASUS router such as the RT-BE86U or RT-BE88U adds multi-gig ports, 4K-QAM and Multi-Link Operation for newer phones and laptops. These sit higher in price but have long support runways ahead.
Large or multi-story homes
Instead of one big router, a mesh system will do more for coverage. ASUS’s ZenWiFi line, including Wi-Fi 7 models such as the ZenWiFi BT8, or any AiMesh-compatible pair of routers, spreads signal more evenly than a single high-power Wi-Fi 5 unit ever could.
Bottom line
The ASUS AC2400 (RT-AC87U) earned its reputation as a fast, feature-rich Wi-Fi 5 router, but in 2026 it is an older device with no ongoing security support and speeds well below today’s entry-level routers. Keep one only as a secondary access point behind a supported router; for your main router, buy a current Wi-Fi 6 or Wi-Fi 7 model.
