Cannot play 3DS Super Smash bros online

[arctic stirrup]

"Error Code: 018-0510 Unable to connect to partner's device. Please try again later. If the problem persists, something in your network environment may be causing connection issues with your partner."
Please help

[fresh flare]

018-0510 (3DS/2DS)

Support code detected, press to expand information

[sharp dawn]

P2P issues, keep trying