Community discussions

MikroTik App
 
NULUSIOS
just joined
Topic Author
Posts: 8
Joined: Wed Aug 28, 2019 11:28 am

3 out of 4 RB751U-2HnD just died.

Mon Sep 19, 2022 5:01 pm

So, I used four of those as simple AP in some work place.
All connected to the network with Ethernet directly to main switch, which is also PoE but I didn't use the PoE (I think it didn't work, but since I wasn't involved in the cabling I didn't look much further) and instead used their power supplies.
They worked fine for years.
I did update them every few months (one by one of course), all ok.

A few days ago, a user noticed that he was losing connectivity and I want in person to see that it actually connected in some of the more distant AP (even though the computer never moved) and not the one 2 meters away.
This was just the beginning.
I tried to connect to all 4 using web.
Long story (really long story) short, 3 of the 4 (mostly) did not connect over the web nor over winbox when I tried alternatively.
Sometimes timeout, sometimes didn't even connect, sometimes "server error" or something (don't remember the wording) and popped back to login, sometimes winbox asked for legacy mode (and it didn't help), sometimes over web it loaded half the page or didn't load any graphics and in winbox scanning sometimes showed 1, 2 or 3 instead of all 4 (and not always the same missing).
While trying, I DID MANAGE to upgrade all 4 to 7.5! Which was also a challenge, because the 3, stopped a few times, before even starting, or while downloading.
In the end they did upgrade. It said 7.5 in winbox, it said 7.5 within the web client, but said an older version in web login screen (which I assumed is just a bug of 7.5?).
Point is, the upgrade didn't help. They still acted up the same.
Only one of the four retained connected clients (which was the reason there was no riot here).

I was forced to switch to a different brand, quickly, both because MT WiFi 6 products were limited (or is it just one?) and because the customer stopped trusting the brand.
The 4 new AP, connected this time over PoE, using same cables that went to same ports on main switch. So nor the cabling or those ports were the issue.

Today I config reset all for to see if it could fix them (using reset button with a pin).
It didn't. One of the four, connected fine to my directly connected laptop, winbox went in using MAC, it asked for password change, all ok.
The other three? Never connected. Actually one even kept disconnecting the actual Ethernet connection until I did a second config reset.
Although their MAC showed up in winbox, it failed to connect and retried (not password issue)... or asked for legacy mode that it didn't help. I never went in.

What could have killed 3 out of 4 MT (about?) the same time?
Any ideas?
 
User avatar
rextended
Forum Guru
Forum Guru
Posts: 9535
Joined: Tue Feb 25, 2014 12:49 pm
Location: 🇮🇹, my 💔 is in 🇺🇦

Re: 3 out of 4 RB751U-2HnD just died.

Mon Sep 19, 2022 5:33 pm

Long story short: use netinstall with 6.48.6 (long-term) and after that, do not use .backup to clone, do not use same IP, do not use same MAC address.
 
NULUSIOS
just joined
Topic Author
Posts: 8
Joined: Wed Aug 28, 2019 11:28 am

Re: 3 out of 4 RB751U-2HnD just died.

Mon Sep 19, 2022 7:25 pm

Long story short: use netinstall with 6.48.6 (long-term) and after that, do not use .backup to clone, do not use same IP, do not use same MAC address.
OK will try that, but note that this happened BEFORE I tried updating them and long after the last update (weeks or few months).
(which was indeed 6.XX)
I updated to 7.5 AFTER the problem happened, to see if it resolves anything reflashing the firmware.
But anyway, will try that too.

About your comment on IP/MAC... Is this because you suspect some kind of hacking?
 
User avatar
rextended
Forum Guru
Forum Guru
Posts: 9535
Joined: Tue Feb 25, 2014 12:49 pm
Location: 🇮🇹, my 💔 is in 🇺🇦

Re: 3 out of 4 RB751U-2HnD just died.

Mon Sep 19, 2022 8:29 pm

Yes, I do not know what are previous RouterOS versions installed....

Who is online

Users browsing this forum: Amazon [Bot], Bing [Bot] and 9 guests