RockPro64 powerful enough as a Plex Media Server?

[dukla2000]

I do not claim full expertise in this area, but for whatever reason I believe the default line has to be first line. (Otherwise it is ignored and the first entry is used - in your case is 4.18 so you should be booting 4.18 either way!!) Did you boot 4.18 after the install? 

Mine is

Code:

$ cat /boot/extlinux/extlinux.conf
default kernel-4.4.138

timeout 10
menu title select kernel

label kernel-4.18.0
    kernel /boot/vmlinuz-4.18.0-rc8-76686-g45828c4db727-dirty
    initrd /boot/initrd.img-4.18.0-rc8-76686-g45828c4db727-dirty
    devicetreedir /boot/dtbs/4.18.0-rc8-76686-g45828c4db727-dirty
    append rw panic=10 init=/sbin/init coherent_pool=1M ethaddr=${ethaddr} eth1addr=${eth1addr} serial=${serial#} cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory swapaccount=1 root=LABEL=MySM961 rootwait rootfstype=ext4

label kernel-4.18.0-rc8-1060-ayufan-g45828c4db727
    kernel /boot/vmlinuz-4.18.0-rc8-1060-ayufan-g45828c4db727
    initrd /boot/initrd.img-4.18.0-rc8-1060-ayufan-g45828c4db727
    devicetreedir /boot/dtbs/4.18.0-rc8-1060-ayufan-g45828c4db727
    append rw panic=10 init=/sbin/init coherent_pool=1M ethaddr=${ethaddr} eth1addr=${eth1addr} serial=${serial#} cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory swapaccount=1 root=LABEL=MySM961 rootwait rootfstype=ext4

label kernel-4.4.138
    kernel /boot/vmlinuz-4.4.138-1094-rockchip-ayufan-gf13a8a9a4eee
    initrd /boot/initrd.img-4.4.138-1094-rockchip-ayufan-gf13a8a9a4eee
    devicetreedir /boot/dtbs/4.4.138-1094-rockchip-ayufan-gf13a8a9a4eee
    append rw panic=10 init=/sbin/init coherent_pool=1M ethaddr=${ethaddr} eth1addr=${eth1addr} serial=${serial#} cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory swapaccount=1 root=LABEL=MySM961 rootwait rootfstype=ext4

label kernel-4.4.132-1075-rockchip-ayufan-ga83beded8524
    kernel /boot/vmlinuz-4.4.132-1075-rockchip-ayufan-ga83beded8524
    initrd /boot/initrd.img-4.4.132-1075-rockchip-ayufan-ga83beded8524
    devicetreedir /boot/dtbs/4.4.132-1075-rockchip-ayufan-ga83beded8524
    append rw panic=10 init=/sbin/init coherent_pool=1M ethaddr=${ethaddr} eth1addr=${eth1addr} serial=${serial#} cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory swapaccount=1 root=LABEL=MySM961 rootwait rootfstype=ext4
chris@rpro64:~$ uname -a
Linux rpro64.dukla.net 4.4.138-1094-rockchip-ayufan-gf13a8a9a4eee #1 SMP Thu Aug 9 20:29:55 UTC 2018 aarch64 aarch64 aarch64 GNU/Linux

<Mine is slightly complicated as I have my rootfs on my NVMe drive, which also means I have to maintain it on both the SDcard that is used for cold boot as well as the NVMe which is used for reboot!>