Do I still need a modem, or does this replace everything?
You still need whatever brings the internet into the building. The RT-AX57 is a router, not a modem: it takes an existing cable modem, fiber terminal or provider gateway on its incoming port and distributes that connection to everything else. ASUS includes an Ethernet cable for exactly that hop. If your provider gave you a combined modem-router, the clean setup is to put that box into bridge or modem-only mode and let the ASUS handle addressing. Leaving both in router mode stacks two layers of network translation, the usual reason game invites break and port forwarding refuses to work.
Will a single unit cover my whole house?
Layout decides this far more than square footage does. Four antennas across two bands give it a fair reach for an apartment or a small-to-medium home, and owner feedback on range leans positive, but feedback on signal strength is genuinely split. That split is usually a placement story rather than a hardware one. Radio hates cupboards, floors, the back of a television and the side of a metal filing cabinet. Put it central, high and in the open before you judge it. Brick walls, foil-backed insulation and large mirrors are the worst offenders in a typical home, and no router argues with them.
Why do my devices never reach AX3000 speeds?
Because nothing is meant to. AX3000 is the two radios added together, the slower long-reaching 2.4GHz band plus the faster 5GHz one, and no device connects to both at once. Your laptop talks to a single band, so the realistic ceiling is that band's rate minus the overhead every wireless link pays. The headline 5GHz number also assumes the widest channel width and a client capable of using it, while most phones and laptops settle at half that width. Wired ports are gigabit, so a very fast plan is capped there too. Mixed owner feedback on speed is largely that arithmetic meeting the box cover.
Can I add a second unit later to cover more of the house?
Yes, and AiMesh is one of the better reasons to buy into ASUS at all. A second compatible ASUS router joins as a node, keeps a single network name, and hands your phone between units as you walk around instead of making you switch networks manually. You can link the node wirelessly, but running an Ethernet cable between them and using that as the backhaul is dramatically more stable, since the node then spends its whole radio budget on your devices rather than on the main router. The unit also runs as a plain access point, a repeater or a media bridge if you already have a router you like.
What does this model leave out?
There is no USB port, so no sharing a drive or a printer from the router and no mobile-broadband stick as a backup line. There is no multi-gigabit port either, which means a multi-gig internet plan would outrun it. The antennas are fixed rather than removable, and the radios are two-stream, which matters most in an apartment block crowded with competing networks. Owner feedback on connectivity is mixed, and the recurring pattern with routers in this bracket is a household with dozens of always-on smart devices asking more of a mainstream unit than it was designed for.
Is the security and parental control genuinely free, and how hard is setup?
Setup is what owners rate most warmly: the app walks you through it, and there is a full browser interface for anyone who wants the deeper settings. AiProtection Classic and the parental controls are included for the life of the router with no subscription, covering malicious-site blocking, infected-device alerts, scheduling and content filtering. Two things worth doing on day one. Turn on automatic firmware updates, since firmware is the standard first fix for intermittent drop-outs. And set Wi-Fi security to WPA3 where your devices support it, with mixed mode as the fallback for older gear.
