Yes, you can keep your router. What you cannot do is let both boxes run the network — and mesh units will not join an existing router wirelessly at all.
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You can add mesh to an existing router, but the main mesh unit has to be connected to it with an Ethernet cable, and only one of the two devices should be routing. TP-Link's own documentation is explicit on both points: a Deco cannot join an existing router wirelessly, and a combined modem-router should be put into bridge mode to avoid double NAT. The same holds across the category.
Three ways to combine them
Arrangement
What routes
Good for
Watch out for
Bridge the old box; mesh routes
The mesh system
Any provider gateway you cannot return
Bridge mode is sometimes buried or needs a support call
Keep the router; mesh in access-point mode
The existing router
A good router with settings you rely on
Not every mesh system offers AP mode — check first
Keep the router; add matched nodes (AiMesh / EasyMesh)
The existing router
ASUS and TP-Link routers that support it
Only works within the same brand's mesh standard
Leave both routing
Both — double NAT
Nothing, really
Port forwarding, console warnings and VPNs break
Pick a row. The first is the cleanest, the second is the compromise, and the third is only for a specific kind of router.
Scroll the table sideways to see every column.
Option 1 — Bridge the old box and let the mesh route
This is the default recommendation and the one TP-Link gives: put the provider's combined modem-router into bridge mode so it stops handing out addresses, then wire it to the main mesh unit's WAN port. You keep the modem function you need and the mesh system runs the network cleanly.
Bridge mode lives in different places on different gateways and a few providers require a phone call to enable it. If you cannot get it, turn the gateway's Wi-Fi off at minimum so two networks are not fighting over the same channels, and accept the double NAT. Whether to replace the box entirely is the related decision, and router vs modem vs gateway explains which box you actually have.
Option 2 — Keep the router, put the mesh in access-point mode
Worth doing when the existing router is genuinely good and you depend on something it does — a VPN client, specific firewall rules, a static address layout. In access-point mode the mesh system stops routing entirely and becomes radios on a wire, with the router remaining in charge.
Two caveats. Not every mesh system offers the mode, so check before you buy rather than after. And you will manage the network in two places, which is exactly the complexity mesh was sold to remove. If you do not have a specific reason to keep the old router, bridge it instead.
Worth knowing
What double NAT actually breaks
Two devices both translating addresses works fine for browsing, streaming and video calls — which is why many households run it for years without noticing. It breaks the things that need an inbound connection: port forwarding, some game consoles reporting a strict NAT type, self-hosted services, and some VPN configurations. If none of that applies to you, double NAT is untidy rather than urgent.
Option 3 — Keep the router and add matched nodes
If your router is an ASUS with AiMesh or a TP-Link that supports EasyMesh, the cheapest upgrade is not a mesh system at all — it is a second unit from the same family. The router becomes the controller, your existing settings survive, and you pay for one node instead of a two-pack. This is also the argument for buying a mesh-capable router in the first place: it turns a future coverage problem into an addition rather than a replacement.
When you should just replace the router
It is a rented provider gateway. Replacing it stops a monthly fee and removes the weakest hardware in the house at the same time.
The full procedure, including firmware and the settings worth changing, is on how to set up mesh Wi-Fi.
What to look for before you buy
If you intend to keep your router, the deciding feature is a documented access-point mode. If you intend to replace it, the deciding features are Ethernet ports per unit and setup simplicity. And if your router already supports AiMesh or EasyMesh, the cheapest correct answer may be one more unit of what you own. The three picks below cover those three routes.
How we picked
We do not run a test lab. Rankings here are built from the manufacturers' published specifications, measurements taken by independent outlets that do have labs, and the structural reasoning on this site about what a given house or job actually needs. Every product was checked as currently sold before it was included. Where a figure appears it is attributed and linked in Sources; where we have no basis for a claim, it is left out. Our methodology sets out exactly what we will and will not assert.
Quick picks
Ranked by our published scoring rubric (works alongside a router, ports, simplicity, value). Tap any row to jump to the full write-up, or go straight to the retailer from the right-hand column. How we score.
#
Product
Best for
Score
Price
1
Illustrative
TP-Link Deco BE63Deco has a documented access-point mode, so the whole system can sit behind your existing router without a second layer of address translation.
eero Pro 7Five Ethernet ports per unit and the least painful setup in the category — the better answer when the honest conclusion is that the old router should go.
Replacing the router instead, and keeping it simple
Scroll the table sideways on a narrow screen. Scores are our editorial assessment from published specifications and independent testing by named outlets — not our own lab results. What we do and do not test.
The picks in full
Illustrative
#1 · Adding mesh behind a router you want to keep
TP-Link Deco BE63
TP-Link · Midrange
The value pick in Wi-Fi 7 mesh: tri-band coverage for a large house at a price the premium systems cannot match.
Key specifications
Standard
Wi-Fi 7, tri-band
Coverage
Up to about 7,600 sq ft as a two-pack
Devices
200+
Also sold as
Deco 7 Pro BE10000 on TP-Link's US site
Score 9.0/10
Works alongside a router9.5
Ports8.5
Simplicity8.0
Value10.0
What it gets right
+The coverage-per-dollar leader in Wi-Fi 7 mesh right now
+Tri-band, so the nodes get a dedicated lane and you do not lose half your speed at the far node
+TP-Link sells the same hardware under two names, which often means one of the two listings is cheaper
What to watch for
−The two-name situation makes comparison shopping genuinely confusing — check the model number on the box
−App is capable but busier than eero's
−Coverage claims assume open-plan space; brick and plaster cut it down hard
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Common questions
Can I add mesh Wi-Fi to my existing router?+−
Yes, but the main mesh unit must be wired to the router with Ethernet — mesh systems cannot join an existing router wirelessly. You then choose which device routes: bridge the old box and let the mesh run the network, or put the mesh system into access-point mode and leave the router in charge.
Do I need to put my router in bridge mode for mesh Wi-Fi?+−
If it is a combined modem and router, yes — TP-Link recommends bridge mode specifically to avoid double NAT. If it is a modem only, there is nothing to bridge. If bridge mode is unavailable on your gateway, turn its Wi-Fi off and accept double NAT, which most households never notice.
What problems does double NAT cause?+−
Browsing, streaming and video calls are unaffected, which is why it often goes unnoticed. What breaks are inbound connections: port forwarding, game consoles reporting a strict NAT type, self-hosted services and some VPN setups. If you do none of those things it is untidy rather than harmful.
Should I keep my old router or let the mesh system replace it?+−
Let the mesh replace it unless you depend on something the router does — a VPN client, specific firewall rules, a fixed address layout. Definitely replace it if it is rented, more than about five years old, or if speeds are poor standing right beside it, because keeping it preserves the real problem.
Illustrative
