How do you set up DNS on a Mercury router? The entrance is hidden in the advanced WAN parameters, and I was in the wrong place on my first trip too

last week, my cousin asked me on WeChat about his Mercury D191G, wanting to bind a MERCURY ID so you can remotely manage the router in the mobile app (I've written about what can be done after binding it Mercury remote management ), but after entering the account and password, the interface kept popping up: 'Request failed, please try again later.' He called customer service, and they said, "DNS might be unstable. Try changing the WAN port DNS." He then searched for WAN port settings in the melogin.cn—flipping through it again and again, the page only showed internet access and broadband account passwords, with no DNS input at all.

I went to the wrong place on my first trip too. Mercury's DNS field box is not on the main WAN port settings page, but is hidden in a subpage called WAN Advanced Parameters under the "Network Parameters" menu. This article will clearly explain the complete path to change DNS on Mercury, how to choose DNS, and the pitfalls that don't work after modification.

to get straight to the point: DNS handles translation, regardless of speed

DNS and it does one thing: you type a website, and it translates it into an IP address. It's like a number inquiry desk—you name it, it gives your phone number.

so changing DNS can fix problems: some websites won't open, domain name resolution errors, routers can't connect to the manufacturer's cloud servers (my cousin's MERCURY ID issue is the last type). The problem that DNS can't fix is clear: download speed won't improve even a minute. My cousin's 500 Mbps broadband test 486 Mbps before changing DNS, then 483 Mbps after the change. These two or three Mbps fluctuations are just errors in the speed , not DNS's fault. Most of those posts online claiming 'switching DNS doubled speed' mistook 'webpage loading faster' for 'bandwidth increased'—webpages are faster because the half-second parsing time is saved, not because the pipes are thicker.

DNS is what it is, and the general tricks on choosing public DNS, I covered more details in the of DNS configurations, which only covers the operations and pitfalls of the Mercury family.

my troubleshooting order: first confirm that DNS is the fault before taking action

Before changing DNS, I had my cousin do a comparison to avoid wasting all the trouble. On his computer, he opened the command line, typed nslookup mercurycom.com, and checked the returned server address—this step checked who the DNS was currently using. Normally, it should return the DNS address issued by the carrier along with a string of resolution results, but the resolution results from his device were intermittent. The same domain name was checked three times in a row, with results twice and a timeout, which matches what customer service called "unstable DNS."

By the way, if your home has "some websites that can't be opened but some can," it's worth checking this way. But if websites can't open and WeChat can't be sent out, that's not a DNS issue. First, check if it's due to unpaid payments or network disconnection issues, and don't mess around with DNS.

one more reminder: my cousin's device is used by the main router. If you convert the Mercury router into an AP or use it as a switch (LAN port cascading), the WAN DNS will be unused—it won't dial anymore, and DNS will be managed by the upper-level device. In this case, changing the Mercury is pointless; you have to go to the upper-level router or optical modem to modify it. How to modify the optical modem? I wrote an article the Telecom optical modem modification DNS, most require over-admin rights, which is much more troublesome than the Mercury modem.

real entry point: Go to the advanced WAN port under Network Parameters

enter melogin.cn in your computer browser (if you can't open it, type 192.168.0.1; both are the same door. If you really can't get in, check can't open the troubleshooting ), enter the management password to go to the backend. Then, follow the path to:

Advanced Settings → Network Parameters → WAN Port Advanced Parameters

. On this page, you'll find the "DNS Server" field. First, enter one, and one backup (the official statement says at least one), then save. I set my cousin to 223.5.5.5 as the first option and 119.29.29.29 as backup. After saving, the page will prompt for reboot or automatic reconnection, and I'll wait for it to finish. Then go back to the backend and click MERCURY ID again in the top right corner to log in—this time, it connects in one go, and the router in the app lights up online.

two common pitfalls are mentioned upfront:

first don't look for on the main page of the WAN port. The WAN port settings page for both new and old firmware only shows internet access and broadband accounts; DNS is not there. If your backend doesn't even match the menu tree for 'Advanced Settings → Network Parameters,' it's probably old firmware with a different interface. Go upgrade the firmware first then check again. On the old interface, Mercury usually has two columns for Preferred Backup DNS at the bottom of the 'Network Parameters → WAN Port Settings' page, with the same logic.

second, the mobile app can't change . In the Mercury WiFi App, parameters like "Internet Settings" are read-only; you can view them but not change them. Changes related to DNS and other network parameters have to be returned to the webpage backend. This is similar to Xiaomi's temperament; you can't even find DNS settings in the Mijia app. I mentioned this in my Xiaomi changing DNS.

DNS which to fill in: In my actual tests

I used latency accounts. Before filling in, I pinged my cousin's house to a common public DNS for your reference (his company uses broadband telecom, so there may be differences depending on the region and carrier):

. My main backup pairing is just one thing: first pick Alibaba, backup Tencent. This combination works smoothly for most domestic routes. The old DNS issue of 114 is quite controversial. Many people online have reported that the results it parses occasionally point to the promotion page, and those persistent small ads popping up in the lower right corner. It's worth checking out the DNS hijacking self-check article—don't just blame DNS selection. Google's unit has high latency and occasionally loses packets, so even filling it as a backup is a hassle. AdGuard is used to filter ads. While browser banners can be reduced by one screen, the 90-millisecond delay is a step slower when the page first loads. Elderly people at home should be cautious—they can't tell which is worse: "no ads" or "laggy internet."

there's another invisible trick to mention: if your home has ever run IPv6 (I wrote about IPv6 on how to use this Mercury model), your phone and computer might be running the v6 DNS lane, and it's still in the carrier's hands. This means that even though the v4 DNS has been changed, some websites are still the same. To check, check the phone's WiFi details to see if there are v6 addresses starting with 240e. If so, either set v6's DNS to auto-follow or simply turn off v6 for a few days to compare. This Dadao 922 article also mentioned in the Guangmao article that the root of the problem between the two families is the same.

the changes didn't take effect? Check each of the three locations one by one

first checking device cache . On the computer, type ipconfig/flushdns command line to clear local cache. The simplest way to turn off WiFi and reconnect on your phone is to turn off WiFi. On the first night, my cousin said, 'No changes even after the changes.' I checked remotely and saw that his laptop's DNS cache still had old records from half an hour ago, but after clearing them, they were immediately back to normal. For devices like TV boxes where settings can't be changed, just cut off the power for half a minute.

Secondly check if there was really a reconnection . After saving the WAN port, Mercury will reconnect by itself, but if you refresh the page at the moment of saving, the reconnection might not be complete. Go to the background homepage to check the WAN port status. Only if it's 'connected' and running data does it count. If you're unsure, unplug and restart the router.

Third, check whether terminal has manually set DNS. The router's DNS only handles devices that are "automatically acquired." If any of your computers have manually entered 8.8.8.6 before, it won't even ask about the router, and even if you change it, it won't interfere. Command line: ipconfig /all Check the 'DNS server' line; it shows the router's address (like 192.168.0.1), indicating it is managed by the router.

conclusion: Who is worth modifying, and who is just a hassle

There are only three situations worth trying: some websites intermittently fail to open, routers failing to connect to vendor cloud services (like MERCURY ID, 'request failures', etc.), or you want to unify FamilyMart's resolution and use AdGuard to filter ads. After changing these three types, you can really feel the difference.

just bored and wanting to "optimize," my advice is to stop. Carriers' default DNS hasn't been as bad as it was in previous years; most regions are fast and stable, and the benefits of switching to public DNS often lie within the margin of error. And for those with poor memories, there's a backlash: in two years, if you switch broadband carriers or restore the router to the factory, you forget to change the DNS back, which means you have to take an extra hour to troubleshoot—I even stuck a note on my cousin's D191G at the bottom, saying "DNS has been changed to 223.5.5.5."

Finally, here's the order: Firstnslookup confirm it's DNS's fault → melogin.cn → Advanced Settings → Network Parameters → WAN Port Advanced Parameters → Fill in Preferred Backup → Save Equal Reconnection → Clear Device Cache → Then Validate. If you make changes, it's even worse. Clearing the fill box to restore auto-acquisition can restore it in a minute. There's no downside to regret medicine—you can always go back on your word.