How to distinguish between telecom optical modems, gigabit ports, and hundred-megabit ports? Gigabit broadband speed is 93 Mbps, so it's almost certainly the wrong plug

Gigabit broadband is installed on the first day, with a speed test of 93 Mbps, your first reaction will definitely be that the operator is lying. I helped three friends check this issue: two were connected to the wrong cable socket, and one was that the cable only had four cores. The identical network ports behind the optical modem can be ten times faster—this is the easiest pitfall to be overlooked and easiest to fix.

clarify first: the last few mouths on the optical modem aren't all the fast

carriers save wherever possible when purchasing optical modems. The network port of the cat at home is most likely a "one gigabit + several hundred-bit" combos. Gigabit ports are reserved for routers, hundred-megabit ports are more than enough for IPTV set-top boxes—4K live streaming traffic is only 20 to 30 Mbps, and they never intended to let you run all eight ports.

the few telecom modems I've handled, the port configuration is roughly like this:

be careful not to wear the model or silk-screen printing. Every cat's port is marked with words: GE is Gigabit Ethernet, FE is 100Mbps, and IPTV is reserved for set-top boxes. When installers, they only ensure 'connected' and not 'fully loaded', so be especially careful if you're reconnecting the wires yourself.

Why do operators adopt this "one fast, multiple slow" combination? Do the math and you'll understand: a full gigabit four-mouth cat and a 1000-300 trillion cat have a purchase price difference of just a few yuan, multiplied by the installation volume of millions of units, which is a huge sum. For most households, the only cable that truly delivers gigabit is the router cable; the rest can be connected to set-top boxes or old desktops, and 100Mbps is more than enough. You're a NAS player who wants whole-house wired connections, which is why you fell into this trap—and you're exactly the one reading this article.

Three tips for identifying the device: No need to disassemble or use tools

first trick: check the silk screen. the cat flips over or closes to the small text above or below each port, GE stands for Gigabit. This is the fastest method, but there's a problem: many cat silk screens are very small and turn gray as they age.

second trick: check the negotiation speed in the backend. open 192.168.2.1, log in with the useradmin account on the sticker (if it won't open, check this troubleshooting entry ), go to the "Status" menu, find "Ethernet port" or a subpage labeled with ETH. The number after each port shows the current actual negotiation speed—100M or 1000M, clearly visible. This is the most accurate of the three, because it reflects how fast this thread is running at this mouth.

third tip: Connect directly to your computer to check the connection speed. network cable plugged directly into the computer from the modem's gigabit port, Win10/11 checked "Connection speed" in "Settings → Network → Ethernet," and Mac in "System Settings → Network." Showing 1Gbps means both the port and cable are fine; showing 100Mbps means the chain has dropped.

a reminder: in the third trick, your computer's own network card must be gigabit. For laptops from ten years ago, the network card is already 100Mbps, so a test of 100Mbps isn't necessarily the cat's fault.

three tricks are used in a certain order: first check the silkscreen positioning of "which port should be gigabit," then go backend to see "how fast this port is actually running now," and finally use a computer for direct cross-verification. If all three pieces of information match, the problem is locked at the most important layer. Just looking at the silkscreen has a pitfall—I've seen a cat silkscreen with GE and the backend negotiating for 100M, but it was eventually found to be a four-core network cable. So the silkscreen can only tell you "the port is fine," not "the link is fine."

My colleague's 93MB cable plugged into the IPTV port

recreate the scene. A colleague moved and installed the gigabit broadband, then he took the equipment back himself. That night, the speed test was 93 Mbps, and he angrily called 10,000 to report the fault. The next day, when the technician came over, the first thing was to check the modem light, and the second was to look down at which port the cable was plugged in—the network cable was firmly plugged into the 100 Mbps port labeled IPTV.

Before

moved, the installer connected to port 1, and when he connected it himself, he would casually plug in whichever port he used, which fit perfectly into the IPTV port. Switching back to port 1, the speed test went straight to 940 Mbps.

here, there's a particularly typical numerical feature: speed cameras stuck between 90~95 megabytes, first check the port. 100Mbps is theoretically 100M, and after deducting protocol overhead, the actual throughput caps at 93~95MB. It wasn't 'slowing down'—it was physically strangled. If your home speed check is 300-400 Mbps, that's a different matter. a complete four-layer checklist for failing speed tests I wrote an article about following that order.

casually give you a numerical comparison chart, so you'll know where to look when you look at the speed test results later:

When

technician left, I asked one more question. He said he could take two or three such orders a day, and eight out of ten were inserted into the wrong port—because from the outside, the 100-megabit and gigabit ports look exactly the same, and the wiring operators wouldn't get close to check the screen print.

plugged in correctly, still 100Mbps: network cable is the next suspect

if the silkscreen is correct and the port insertion is correct, negotiations still won't allow 1000M to reach 1000M, shifting suspicion onto the network cable. For 100Mbps, only four cores of 1236 are needed in the network cable, while all eight gigabit cores are fully connected—this leaves room for "half-broken cables" to survive.

three most common types:

• wires buried in the walls of old houses, back then only four cores were installed, running 100 Mbps was fine, but over gigabit cables directly ruined
• handmade crystal connectors, with only six or seven 8 cores connected, impossible to negotiate with gi
• gabit wall power strips or through connectors oxidized or misaligned wiring. The most hidden incident I've seen was a loose core on the back of the panel

fastest way to eliminate: find a machine-made Cat5e jumper cord and connect it directly to the computer via the Cat's gigabit port. If you negotiate 1000M, it means the original cable has a problem. The pitfalls and wiring sequences in renovation wiring are important. I have written about them in more detail in this renovation network cable planning .

Light modem itself is a 100-megameter modem: three-step confirmation, free

there's another situation that's even more unfortunate: the wire-to-antenna pair, but the cat itself is a mega-cat. Before 2015, many of the cats installed had 100Mbps LAN ports. Back then, 100Mbps broadband was sufficient, but later broadband was upgraded to gigabit for free. The cat didn't change, and the bottleneck remained with the cat.

confirm if this is the case, three steps:

first step, check the silkscreens—all the mouths are FE, not a single GE; Step two: Check the Ethernet port information in the backend; the maximum specification for all ports is 100M; Step three: Go online to search for the model parameters; the info page will say "10/100Mbps." Three steps to match, and the hundred-megapixel cat is definitely running.

ways to replace the cat: the optical modem is the operator's asset. fault reporting is free, don't buy yourself. Call 10000 and just say, 'The fiber modem network port does not support gigabit, broadband is gigabit,' and the technician will bring you to your door. If you buy a cat online, you have to register it through the LOID process yourself. I've gone through that process once and recorded it in the of the Guangguang Cat article. It's not recommended for beginners. If your broadband installation is already gigabit modem, you will definitely use a gigabit modem, so you can skip this section.

there's also a situation caught in the middle: the cat is a gigabit cat, but your broadband is a hundred-megabit. This kind of modem doesn't require a modem; upgrade broadband to above 200Mbps first—nowadays, many places offer free speed boosts on integrated packages, and both modems and cables can handle it, so it doesn't cost much. On the other hand, if broadband upgrades to gigabit but the modem doesn't change, it's the same process as above. Don't complain about the hassle—the difference between 93 Mbps and 940 Mbps is something you use every day.

after switching cats, there are two things to clean up: bridge users need to copy the VRAN and bridge system again, and do the same as in the bridge section; Just disable the WiFi on your new modem, or it will become another source of interference. If you don't know how, check out the article Optical modem WiFi.

Wrap-up: Follow the five steps in order, avoid detours

93 trillion fall into the first three steps. Finish these five steps yourself before reporting the obstacle. The technician can handle it in ten minutes, so don't go back and forth and wait three days.