I have a tplink wr1043n v5.
I installed luci, openvpn and I use vlans.
Openvpn is not capable of lifting the tunnel against a finisher.
With the same configuration I have a wr 1043nd v4 that works correctly, in version 17.01.2.
It seems that the tun device does not work correctly
I have the same issue. But I also had some installation problems when installing openvpn.
Basically I installed openvpn "too late" (see https://openwrt.org/releases/snapshot)
snapshots are built daily, and that sets time limits to installing new packages with opkg. Due to kernel version checksums, you can only install “kmod” kernel modules and other kernel version dependent modules from the exactly same snapshot build. So, a few hours after flashing the firmware you may not be able to install new modules with opkg any more (as the next snapshot has been built into the download repo and has different checksums).
so what are the exact versions of openvpn and kernel on your wr1043n v5?
I just solved this after sysupgrade and reinstalling openvpn