Greetings. Which cards for certs/Dude are supported? I tried 64GB Class10 cards from popular vendors, such as Sandisk, Samsung, Apacer and nothing worked. Is there any 100% supported card, or the full situation is total roulette?

What do you mean with "tried" and "not worked"?
Just inserted a card and expected magic move of Dude data to the card?

simple:

>disk print
# NAME LABEL TYPE DISK FREE SIZE

yes, i did full restart with powering off.

Did you partition and format it?

Yes. Tried ext3 and fat32 (as it was written on wiki). Tried without partitioning. Tried NTFS. Can't see it.

I have a device CCR1009-7G-1C-1S+ but the same problem is that the micro sd slot does not work, I have turned off the device and then entered the micro sd and then restarted the device but the micro sd remains unreadable. Already contacted Mikrotik Support but until now have not received a solution.

I have three CCR1009-7G-1C-1S +, and none of them works with microSD cards.
It seems that this is not a card reader but a card holder.
The same "convenient" feature was in D-Link DFL-260 and 860 (with only USB ports)... you could store USB flash drives in them

You can use a USB drive on the CCR but it requires to use the (included) adapter cable... a little inconvenient since it dangles off the front.
In the RB1100 AHx4 it is much easier to add storage.

Any luck finding and using microSD card for Dude DB on CCR1009-7G-1C-1S+, anyone? What's the maximum capacity supported?

Any luck finding and using microSD card for Dude DB on CCR1009-7G-1C-1S+, anyone? What's the maximum capacity supported?

You can put card of any capacity and any FS type into the CCR1009-7G-1C-1S+ . But you cant use them by design.

I use SanDisk 32GB SD cards and 8GB Kingstone DataTraveler USB sticks and works nicely in many CCR1009xxxx
I have not tried large ones because I have no need for larger ones BUT I see no reason they would not work.

I tried ScanDisk 16G microSD card and it doesn't work. The CCR1009 cannot discover it.

my ccr1009 always loses sdcard after firmware upgrade

but i discovered magic rule of 2(3) reboots
1. upgrade firmware, reboot. card lost
2. extact card, reboot
3. insert card and wooala!

its not directly connected to FW upgrade. any restart makes sdcard eliminated from disk menu. luckily need for reboot happens quite rare