I don't understand... I did nothing and now works.... : |😨
/dev/dri$ cat /usr/syno/etc/codec/activation.conf
{"success":true,"activated_codec":["h264_dec","h264_enc","mpeg4part2_dec","aac_dec","aac_enc","vc1_dec","vc1_enc","hevc_dec","ac3_dec"],"token":"c4bb153f19962434ab57a7bcb7abd93b"}