Ingolf Steinbach wrote:
[...]
> we1 at isa0 port 0x300-0x31f iomem 0xcc000-0xcffff irq 10
> we1: WD8013EPC Ethernet (16-bit)
> we1: Ethernet address 00:00:c0:20:6b:63
> [...]
> boot device: wd0
> root on we1
> nfs_boot: trying RARP (and RPC/bootparam)
> we1: device timeout

Well, it turns out that my ISDN card was configured to use
irq 10, too, (it used irq 5 on 1.5.x). After correcting the
collision, I can boot via NFS. Thanks to all who have spent
time on my problem.

Regards
    Ingolf