Actually, on jessie, you can just install wireguard from unstable:

  https://www.wireguard.io/install/


On Mon, Jun 26, 2017 at 06:40:59PM +0300, Шварц Сергей Владимирович wrote:
> Ibrahim,
> 
> I've rebooted the server and now it's ok.
> 
> Cheers,
> Sergey
> 
> 
> 2017-06-26 14:55 GMT+03:00 Ibrahim Tachijian <barhom@netsat.se>:
> 
> > Hello Sergey,
> >
> > You have probably recently done an apt-get update upgrade that installed a
> > newer kernel-image.
> > I believe if you run,
> >
> >
> >    - apt-get update and upgrade
> >    - reboot
> >    - rebuild wireguard from source (make, make install)
> >
> > Then wireguard should work for you.
> >
> > On Mon, Jun 26, 2017 at 1:35 PM Шварц Сергей Владимирович <
> > svschwartz@gmail.com> wrote:
> >
> >> Hi guys!
> >>
> >> I've build debs for jessie from unstable dsc, but wireguard module failed
> >> to load
> >>
> >> [34282909.202963] wireguard: Unknown symbol __sk_mem_reclaim_amount (err
> >> 0)
> >>
> >> am I doing something wrong or is it jessie simply not supported ?
> >>
> >> Regards,
> >> Sergey
> >> _______________________________________________
> >> WireGuard mailing list
> >> WireGuard@lists.zx2c4.com
> >> https://lists.zx2c4.com/mailman/listinfo/wireguard
> >>
> > --
> > *Ibrahim Tachijian*
> >
> > CEO Net Sat AB
> > Mobile: +46723321377
> > barhom@netsat.se
> >
> > _________________________
> >
> >
> > *Net Sat ABC/O Jayway AB*Klara Östra Kyrkogata 2B, 1TR, 111 52 Stockholm,
> > Sweden
> > Office: +46 (0)8 408 394 53
> >

> _______________________________________________
> WireGuard mailing list
> WireGuard@lists.zx2c4.com
> https://lists.zx2c4.com/mailman/listinfo/wireguard