How do you connect two routers to a telecom optical modem? Both dialers always clashed, so I helped three families pick up before I could tell the three different ways to connect
last month, my cousin renovated his house and took a retired Mercury D191G from me, along with his own newly bought Redmi AX3000T, making two routers. His first question was: With so many ports behind the optical modem, if each router connects one port, can the speed double? I laughed at that moment. I took over this for the three families, and each of them started by asking like this. Here's the conclusion: it's fine for both routers to connect to the fiber modem, but absolutely cannot dial both . One broadband account can only be dialed at one time at a time, and the second router will kick the first offline, kicking back and forth, causing the whole family to be intermittently unable to access the internet.
remember one iron rule: you can only dial one number per broadband
broadband dial-up uses PPPoE, your broadband account is only allowed to 'hang up to one session at a time' in the carrier's billing system. The first device dials in, and the second device tries to dial with the same account password. Usually, there are two outcomes: either you get an error and the account is already taken; Or kick the previous one off and go up yourself. That night, I tested it like the latter: AX3000T dial it first, everything works fine, then dial the Mercury D191G, AX3000T all devices on that side disconnect, wait for the Mercury to be kicked, AX3000T automatically redial back. The two routers kept running all night, and the WiFi icons on our phones spun around until we started questioning our lives.
So, the essence of "connecting two routers to the optical modem" isn't about plugging in the cables, but about figuring out who dial and what the other unit is . Once you figure this out, the connection becomes perfectly natural. Some may ask, why not just get two broadband lines? That's a different matter—one line per account, and ordinary families don't need to get an extra broadband just for an extra router.
Before
start, check which mode your optical modem is on
Telecom optical modem has two working modes, directly deciding which connection method to use. The method is quite rustic, but very accurate: plug your laptop directly into the optical modem's network port 1 with a network cable, and you don't need to tap anything.
| phenomenon | optical modem mode | where anyone plugging in a network cable |
| dials in can access the internet directly | router mode | The optical modem itself |
| pop up a "Broadband Connection" prompt in the lower right corner | bridge mode requires router dialing |
now when installing telecom devices, technicians default to setting the optical modem to router mode. When you enter the 192.168.2.1 backend you can see that WAN connections are in routing mode and WiFi names start with ChinaNet—basically like this. The bridging mode is usually modified later or installed to separate the VLAN for IPTV. My cousin's house and my aunt's family both use the default routing mode. The guy at the third place tried to switch to super password bridge, and I've tried both methods myself.
Method 1: Optical modem router mode, switch both routers to APs (beginners copy this setup
This is the most recommended connection method for ordinary people. The optical modem continues to be the dialer, and both routers have degenerated into "network port extenders with WiFi," which is AP mode. In short: the LAN port of the optical modem has two network cables, each plugged into the LAN port of the router. Note that it's a LAN port, not a WAN port.
specific operation, each machine does two tasks. AX3000T the Redmi 192.168.31.1 backend, in the common settings there is a working mode. Switch to wired relay mode (some firmware calls this access point mode). After switching and rebooting, it will function as an AP, with DHCP and dial-up disabled. Older machines like the Mercury D191G don't have a mode switch, so do it manually: turn off the DHCP server on the melogin.cn, then change the LAN IP to one that shares the same subsidiary but does not conflict with the optical modem. For example, if the modem is 192.168.2.1, set the Mercury to 192.168.2.3 for easier access to its backend later. The network cable comes out of the optical modem port 1 and plugs into the Mercury LAN port, and that's it.
advantage of this connection method is that all the devices in the family are on the same network. Phones connect to AX3000T WiFi in the living room, Mercury WiFi in the bedroom, and TV casting and accessing NAS without separation. The downside is obvious: the optical modem's routing performance is generally weak, and the number of devices you carry is small. My Huawei device started occasionally freezing after about twenty devices HS8145V5 been connected. If you don't have many devices at home, this drawback is basically not noticeable. I previously wrote a detailed article comparing the wiring methods used by router as a switch in a single unit to an AP, the wiring is universal.
Method 2: Switch the optical modem to bridge, dial the main router, and the second device hangs the main router below
you have a NAS at home that needs remote access, port forwarding, or gaming that requires NAT type, just the modem router mode isn't enough—you need a high-performance router as your main tool. The connection for this setup is: optical modem (bridge, only for photoelectric conversion), → AX3000T WAN port (PPPoE dial-up), → AX3000T LAN port→ Mercury (converted to AP, same connection method as above).
to change bridging, you need to use the optical modem's super administrator privileges. The useradmin account doesn't have this permission, so you need to use a telecomadmin-level superadmin account to go to network settings and change WAN connection. Change the INTERNET link to bridge and check the corresponding VLAN. I explained in detail how to get the password in the super password . After making changes, remember to enter your broadband account and password into PPPoE on the router, otherwise your whole family will be disconnected. One more thing to be mentally prepared for: some provinces' ITMS systems will push the bridge configuration back to routing mode after changing it at midnight. I once fell into the trap of going back to before liberation overnight, ITMS pushed back to that , there are three countermeasures.
the division of labor in this setup is: AX3000T dialing, DHCP, handling all routing tasks, while Mercury only assists in amplifying WiFi signals. The performance ceiling is much higher than the first wiring method, but the trade-off is having to use the optical modem and worry about ITMS. If you're a beginner just wanting WiFi in another room, don't mess around with it right away.
What to do if the
modem port is insufficient: add a switch in the middle
When
connect, you'll notice a practical issue: there aren't many mouths behind the cat's butt. Huawei HS8145V5 these common models: port 1 is gigabit, port 2 and IPTV port are 100Mbps. Two routers, a TV, and a NAS are simply not enough to separate them. At this point, don't force it. Add a non-managed gigabit switch in the middle, costing fifty to sixty yuan. Connect the optical modem's network port to the switch, and attach anything underneath the switch.
both routers shouldn't be plugged into 100M ports; gigabit broadband is locked around 93MHz once it passes through 100Mbps, and speed tests can be frustrating. Which port is gigabit and which is 100Mbps, you can identify GE and FE by the silkscreen mark, or check the negotiation speed in the backend. I wrote an article the distinction between optical modems, gigabit and hundredMbps, specifically this topic. There is also a buying guide how to choose and connect a switch. For home use, just buy non-managed gigabit models with your eyes closed.
I've stepped through three pitfalls for you
first pitfall: both cars run DHCP. This is the easiest and hardest to detect, manifesting as having half the devices at home that can access the internet and half not, or sometimes good, sometimes broken, because devices randomly take IPs from two routers, and if they pick the wrong ones, there is no gateway. The rule is simple: there can only be one DHCP across the entire network. Connect to the first mile to the optical modem, connect to the second li to the main router, and the secondary router must be turned off. If half of the devices really get disconnected, first check if the two router segments are colliding. the method from the in the IP fight, apply it directly.
the second pit, the secondary router is connected from the WAN port. Some people casually plug the cable from the optical modem into the secondary router's WAN port, adding an NAT layer to the secondary router, turning it into a network-in-net. You can access the internet, but you can't find devices for TV casting, and computers can't access each other, leaving you completely lost. The iron rule for AP connection is LAN LAN unless the machine is explicitly set to AP/relay mode.
third pitfall: using two WiFi devices with the same name as mesh. If both routers set the WiFi name and password to the same, the phone will indeed "connect," but it will only stick to the first router to connect and won't switch to weak signal areas, because these are two separate routers, not a Mesh system. If you really want seamless switching, you need to buy a network machine from the same brand that supports Mesh. Mesh networking article covered everything. Separate WiFi names for both routers actually saves you the hassle.
Ending: Take the Position Before Taking Action
| your situation | which one should you choose |
| If you don't want to mess around, just want to have more rooms with WiFi | connection. Method one, two units can be fully replaced AP |
| have NAS/port forwarding/NAT requirements | Method 2: optical modem bridge + main router dial-up |
| optical modem port not enough to plug in | arbitrary connection + add gigabit switch in the middle |
| both are Mesh models from the same brand | just build a Mesh setup—don't use the method in this article |
follow this step: first distinguish the optical modem modem, then decide who dials the number, then switch to secondary routers (turn off DHCP, LAN to LAN), and finally unify WiFi names and separate them. Leaving half an hour for the whole process is enough; switching to the bridging system is another matter. My cousin's house ended up using method one: two routers, one for the living room and one for the bedroom. We ran around for a month without any trouble.
