wget: limit downloaded bytes problem

[Bastian Bittorf]

With OpenWRT master and busybox v1.34.1 (musl-1.2.2),
but also with older busybox v1.26.2 (musl-1.1.16),
I see these issues with wget:

# on server:
dd if=/dev/urandom of=/var/www/random.bin bs=513 count=1

# on OpenWRT/client: limit downloaded bytes:
wget -O - http://intercity-vpn.de/random.bin | head -c 10 >/tmp/part
(hangs/connection times out)
 ^^^^^

The interesting things are:
1) sometimes it works
2) no problem with files =< 512 bytes

i tried it with different architectures:
OK: mipsel_24kc / ramips (Archer C6U)
problem: x86_64 (qemu)
problem: mips_24kc (TP-Link 4300)
problem: ppc/powerpc_8540 (TP-Link 4900)
problem: arm_arm1176jzf-s_vfp = bcm2708/armv6l/RaspPiZero

using GCC8 or GCC11 makes no difference.
using 'curl' instead of wget works without issues.

A selfcompiled static musl-busybox + qemu x86_64 has no issues.

Can somebody confirm this?
Has somebody an idea why i can see this only on OpenWRT?

bye, Bastian