The container actually started after some adjustments. When starting this error pops up:
lxc-start: server: utils.c: safe_mount: 1179 No such file or directory - Failed to mount “/usr/lib/lxc/rootfs/proc/tty” onto “/usr/lib/lxc/rootfs/proc/sys/net”
This is the corresponding config file:
lxc.arch = armv7l
# Container specific configuration
lxc.rootfs.path = dir:/srv/lxc/server/rootfs
lxc.uts.name = server
lxc.mount.fstab = /srv/lxc/server/fstab
# Network configuration
lxc.net.0.type = veth
lxc.net.0.link = br-lan
lxc.net.0.flags = up
lxc.net.0.name = eth0
lxc.net.0.hwaddr = 62:ea:49:85:74:82
lxc.net.0.veth.pair = vethvm1
lxc.include = /usr/share/lxc/config/common.conf
lxc.hook.start-host = /usr/share/lxc/hooks/systemd-workaround
#sda/1
lxc.cgroup.devices.allow = b 8:0 rwm
lxc.cgroup.devices.allow = b 8:1 rwm
#sdb1 sdb
lxc.cgroup.devices.allow = b 8:16 rwm
lxc.cgroup.devices.allow = b 8:17 rwm
#btrfs-control
lxc.cgroup.devices.allow = c 10:234 rwm
#fuse
lxc.cgroup.devices.allow = c 10:229 rwm
lxc.hook.autodev = /srv/lxc/server/mknod.sh