Why do i get this error when trying to set up VPN in openwrt, and why are the ciphers not even supported? How do i fix it? How can i build the latest openvn, or the one that supports the VPN? Seems like it's downgraded or not written in the best way..
If you want assistance, provide more details.
For example:
What VPN technology are you referring to? 
Configs?
OpenVPN.. Might be old. Anyone on here know how to fix it, or howto set up openvpn on openwrt?
Sure, but again:
I think other's would be better able to help you with the issue - when you provide details.
Perhaps additionally, please explain what you did to get these error messages, etc.
I thought that someone here might have had this issue, because when i searched it up it was common, but what i did to try and fix it did not help me personally.. it's openvpn that's the issue. Their code.
If it's their code as you claim - and you did nothing to an OpenWrt to setup a VPN, nor configure it to produce what you're quoting, nor executed any command:
You may wish to ask in in a more appropriate place.