Cannot mount my ext3 partition (on extended partition)

[vdk]

I see two possibilities:

1. Number of partitions: this is probably not the source of the pb since none of the partitions formatted on ubuntu as ext3 worked (only ntfs). I had to rebuild the fs for it to be recognised...
2. Particularities of the ext format: Maybe ubuntu adds some information that is incompatible on the router. I noticed that ubuntu remembers partition labels which seem to be stored on the drive.

I'll sacrifice my ntfs partition (which is almost empty) and convert it to ext3 on ubuntu to investigate, but any hints or leads are appreciated. If I find something, I'll post the solution here (and edit the problem description).

All partitions must be PRIMARY, not Extended, and formated as ext3 or FAT32.