Nintendo 3DS V6.3.0 lock flashcard
Nintendo released new 3DS V6.3.0-12 system on Sep 13th, it improved the safty and compatibility. Some R4 card are locked by the new 3DS system, and some others still work well. Please check the compatible R4 card list before update your 3DS console.

R4 card for 3DS V6.3.0-12
Below r4 cards support 3ds V6.3.0 perfectly.
R4i SDHC card from r4i-sdhc.com (only the r4i sdhc 3ds rts card)
R4i Gold card from r4ids.cn (only r4i gold 3ds rts card).
R4i Dual Core and R4isdhc RTS card from r4isdhc.com.
R4i Gold Pro from r4i-gold.com.
R4i Gold Plus from r4ids.com.
R4i-Gold 3DS card from r4i-gold.eu.
R4iTT RTS card from r4itt.net.
Ace3DS Plus card from Ace3ds.com. (produced after Sep 3rd).
New TT 3DS card from n3dstt.com.
R4idsn 3DS card from r4idsn.com.

R4 card not support 3DS V6.3.0
Below flashcard can't work on latest 3ds console at the moment.
Supercard DStwo from supercard.sc
M3i zero from m3adapter.com
Acekard 2i from acekard.com
Gateway 3DS card from gateway-3ds.com
EZ-Flash from ezflash.com