I am having a intermittent problem not being able to login via web browser on a CSS326 switch. Login attempts fail on Chrome, Firefox browser and Edge browsers. The CSS326-24G-2S+RM switch was installed in October of 2025. Configured for fibre in December 2025. Configured for VLAN's February 2026. The login issued was identified in February.
Until February the switch wasn’t accessed much. It was the fiber introduction and getting VLANs established that the login issue was noticed.
Using browser to access the switch, a pop-ups screen for name and password appears. Entering the data and pressing enter no login and the pop-up reappears.
A reboot of the switch restores web access until the next time login attempts fail.
The issue does not appear on a second same make, model & SwOS version CSS326 that is deployed.
Current Installed Version Mikrotik SwOS 2.18 (built at Wed Jul 02 2025 04:20:30 GMT-0500 (Central Daylight Time))
An nmap scan slows http is listening.
sudo nmap 192.168.42.3
Starting Nmap 7.80 ( https://nmap.org ) at 2026-02-24 09:49 CST
Nmap scan report for 192.168.42.3
Host is up (0.00060s latency).
Not shown: 999 closed ports
PORT STATE SERVICE
80/tcp open http
Does this happen with Webfig (browser) only (or also with Winbox and/or ssh)?
From what you write it could be both a html issue of some kind or something in configuration.
You won't like the first thing to troubleshoot the issue I will suggest, i.e. to exchange the unit with the other one (if in the "other place" the switch works, this would exclude a "hardware" or "storage" issue and point to something in configuration).
I am not familiar with the webfig browser. I’ve only discovered one way to access the CSS326 and that is with a web browser. The SwOS doesn’t appear to have an option to enable SSH. Well I haven’t found it.
I have tried going direct to the swith by typing the URL into the browser or via winbox that fills the URL after firing up a browser.
I physically visited the site today to try and gain access. A reboot no longer gets me access. I am locked out. CRAP!!!
The first time this happened, I was on the browser and failed to use the logout before removing my network connection on the laptop. Note to self “don’t do that anymore”. I restored access by powering the switch down and got back in with the same password.
That powering down option isn’t working anymore:( I’ve tried numerous browsers with no success. I even attempted a connection with lynx a linux text based web interface.
After entering admin and password pressing enter generates a screen flash and the login box is back. It doesn’t appear to be actually trying???
Unfortunately the switch is in production. I’ve made myself available during production downtime to troubleshoot.
I read on a forum post something about a % symbol in password. That is what is in this password. It was not a confirmed issue just speculation. I had hoped gaining access I could change that PW character to see if the problem goes away.
This issue has forced me to purchase another unit. Call it backup, spare whatever. The current switch is working. I like to keep it that way until I have a replacement. The ten or so power downs this morning made me nervous if the unit decided not to come back. I don’t have a spare.
I do have a backup of the configuration that is installed on the switch. Funny, I was try to make backup when I discovered I couldn’t gain access.
I’m not aware of other ways to access the switch. nmap scan shows only port 80 open so if ssh is there it is not on.
Holy Crap, I’m communicating with the points leader on this forum. Sorry for not genuflecting:)
I visited the site one more time before leaving work to throw a hail mary. The operation was down for maintenance. It gave me a chance to isolate the switch and try connecting to the address direct and not over the network.
No joy:( Same. I even dropped the power on the unit (didn’t tell anyone) and still the same. This is where the rabbit hole end hits me in the face.
The supplier suggests one week to receive a unit. I’m taking vacation next week so that puts this on the back burner until sometime after March 26. I hate having a sword of Damocles to come back to but it is what it is.
To follow-up on your suggestions when the unit is available.
I was going to use the switch reset to gain access (if works) and load the configuration currently installed to see if I gain access. If that works what do you suggest as a follow-up? Unless I can identify an issue, I’m reluctant to put it back into production.
Well, that points system - at least in my specific case - is rather meaningless metrics, it doesn't reflect my knowledge/experience, it rather means that I am a prolific poster with a friendly attitude.
I mis-read your model as CRS, and I can imagine a few possible settings that may cause the issue you are having on RouterOS, but on SwOS I have no ideas.
The usual recommendation is to not use special characters, see point #29 here: GP & CSA for Mikrotik devices
outside of the ASCII 7 bit set, because of possible different character encoding, so "%" should be fine.
So, if the issue is not on the browser side (cache, strange auto-save something, etc.) logically it can only be some kind of corruption of the device storage.
This - due to the way flash is organized - could be a rare "bad sector" that was not mapped as such when the OS was deployed or one of those intermittent failures that populate the worst nightmares of electric and electronic engineers attempting to troubleshoot one of these issues.
Your device is (should be) a recently bought one, personally I would - once you get the replacement - RMA it, if it is possible under warranty.
Even if with a reset you re-gain access to it you cannot be sure that the issue would not represent itself (if the issue is with storage).
Usually the seller (where you bought It) should provide the warranty fulfillment, receiving the device back and either repairing or replacing It, but It depends on the country, local Laws, etc., cannot say what applies to your case.