Couple hours ago I had power outage for 2-3 min and after that my RB751U-2HnD couldn't boot. He was rebooting continuously: LEDs start to blink, then they all turn down, power up again, and so on. At first, I thought he is dead so I decided to give it a try and reset it with button and that went fine (otherwise I wouldn't be writing this ). Then I tried to load latest backup file which throw me back in previous situation, again I reset it and load some older backup file which also gave the same result. That RB came with 5.20 ROS, but couple days ago I upgraded it to 6.12, then downgrade it to 5.26, and it was forking fine 'till now.

Biggest problem here is that I had a lot of settings configured on him and I need to get that back 'cause it's soooo lame to do it again. Not to mention that I forgot what I had on him. I mean, I can recreate all the tings, but maaaaaaaaan it will take time

Does anyone have any advice?
Is there any way to realize what's going on and why he is constantly rebooting with old settings?

Try better power adapter.

But what does power adapter have to do with booting after reset and not booting after loading backup file?
I'm using 12V 1A currently...

As i understand now if you remove configuration it repeatedly reboots and if you put configuration back it stops rebooting?

No no no, he don't want to boot (well he boot up, then reboot, and so on) with configuration that I had on him (including backup files), but when I reset him on button he boot fine with default configuration. If I try to load backup he start constantly rebooting again. Get it?

Ok. Got it. If you do not have export script to import it instead the binary backup, you need to configure manually. Maybe you can try netinstall the same version you have the backups and try again. The power supply can be the reason also. Can happen that with backup. It has bigger consumption than resetted device and partially broken psu is insufficient and can be unstable.

Tnx for the info.

I'm not sure what's going on, I also had problem before reset with Huawei E173 3G modem. He was only recognizing it for sending SMS, but I couldn't enable receive sms or see it as ppp device. After reset to default he see it now properly. Strange...

Maybe I will go with this and reconfigure it manually, at least it will serve as a reminder for some forgotten things

What power supply you are suggesting to get?

Mikrotik devices are capable to receive 8-30v. Better to use 20-24v psu than 12v. And to use psu with at least 50% more amp rating that device require according the label.

Ok, I'll try to find stronger adapter.

Ok, I surrender...

I was messing around with configuration, trying to make it like before and, for no reason, I decided to try to load old backup file and guess what..? It worked!!!

I go to sleep now...

Happy boy. Congratulations.