VMG4927-B50A in bridge mode disables admin login

mss1911

I've been using the VMG42927-B50A stably in bridge mode for a year now, (It is the DSL bridge to a Mikrotik router which is the backbone of my homelab) and overall it does its job quietly and without complaint, and I have no issues. Except for one minor nagging complaint:

Once the Zyxel is put into bridge mode, GUI admin login becomes disabled! I can only re-login again by doing a factory reset. The GUI login webpage at 192.168.1.1 does, in fact, load just fine in my browser. But using "admin" and either the default password (or one that I reset it to), it fails the login with "Incorrect password" every time. It doesn't seem to be an actual incorrect password issue though. It's not a captcha issue, and it's not an issue of plugging into the correct ethernet/LAN port (I've tried them all). I understand the web interface login is disabled when a telnet session is in use, but that's not the case. In fact, telnet and ssh time out if I try to log in that way (nmap reports that ports 22 and 23 are filtered). My firewall is permissive for these scenarios, so that's not the issue either.

99.9% of the time, I have no need to log in to the device, so usually this isn't a problem. But once in a while, I need/want to log in directly to check some network diagnostics as close to the source as possible. And if I wanted to reconfigure it out of bridge mode without resetting the device, I'm out of luck. It's annoying to have to factory reset and re-configure it just to login, for multiple obvious reasons…

Is this intended behavior, that admin login is disabled when the device is in bridge mode? If not, is this a known issue? Is there a firmware update that addresses this? Am I overlooking something silly? I searched the device manual but found no clues.

Thanks!

bahecz44120

set your laptop or pc with static IP to same subnet as 192.168.1.1 and you can access to GUI under bridge mode.

mss1911

I'm wondering if you saw the part where I wrote, "The GUI login webpage at 192.168.1.1 does, in fact, load just fine in my browser," because I already connect to it with a static IP on the 192.168.1.1/24 subnet. Accessing GUI login page is not the problem. Getting the GUI login page to accept any login/password combination is the problem. I think that all logins become disabled in bridge mode, and the only way to login is to do a hardware reset of the device. And then magically, the admin login/password suddenly start working again! (Until I put it back in bridge mode)

Peter2

You can define a new extra interface group for your modem for VDSL binded to a Lan Port eg reserve Lan1 that is used for uplink as Modem to your Router WAN Port . Then login over Wlan or the other Lan ports for bridged Router as Modem to GUI .

mss1911

Hi Peter2,

Thanks for replying with your suggestion. Before I do yet another hardware reset on my router, could you please perhaps explain how your method would solve a login authentication issue? (i.e. the GUI tells me "password is incorrect")

Peter2

Of course i cant do this because i dont have your situation .

You can try out or not . If you dont know how to realize it you should tell it instead of being critical .

If you install it succesfull you can get a way to have a look into the bridged modem at work .

With this bridged Modem-Router - with 4 Lan ports that you can separate - you are in a better situation compared to a simple Modem that has only one Lan port …

mss1911

Thank you again for your kind consideration.

• "Of course i cant do this because i dont have your situation ."

I think there is an honest misunderstanding. I was not asking you to actually try this yourself, of course that is not possible. Instead: I was just honestly curious why your suggestion to try a network layer 2 & 3 (i.e. data link / IP layer) tactic could solve an authentication issue into the router's GUI.

Again, I have no problem to access the GUI login page via HTTP. Instead, authentication is the problem, and I suspect the reason is that bridge mode disables all accounts. But if my assumption is invalid, I am hoping for someone to educate me. I think people keep thinking I am having problems accessing 192.168.1.1, but that is not what I am saying.

• "You can try out or not ."

Several other people depend on this internet connection here, so I have only limited chances to explore this, since resetting the modem interrupts everybody else's internet connection here. Then they get grumpy at me :) So, it behooves me to learn as much as I can first, to prepare for my limited opportunities to troubleshoot this.

• "If you dont know how to realize it you should tell it instead of being critical ."

I did not intend to say anything critical. I am just curious why this explanation would fix it. I find it of utmost importance to understand "why," not just "how" :) If you could explain the reasoning to me, I would be very grateful.

Thank you again!