Comment 4 for bug 1883316

Having the same problem:
DKMS make.log for wireguard-1.0.20200611 for kernel 4.4.0-128-generic (x86_64)
Sun Aug 30 18:55:58 CEST 2020
make: Entering directory '/usr/src/linux-headers-4.4.0-128-generic'
  LD /var/lib/dkms/wireguard/1.0.20200611/build/built-in.o
  CC [M] /var/lib/dkms/wireguard/1.0.20200611/build/main.o
  CC [M] /var/lib/dkms/wireguard/1.0.20200611/build/noise.o
  CC [M] /var/lib/dkms/wireguard/1.0.20200611/build/device.o
  CC [M] /var/lib/dkms/wireguard/1.0.20200611/build/peer.o
  CC [M] /var/lib/dkms/wireguard/1.0.20200611/build/timers.o
  CC [M] /var/lib/dkms/wireguard/1.0.20200611/build/queueing.o
  CC [M] /var/lib/dkms/wireguard/1.0.20200611/build/send.o
  CC [M] /var/lib/dkms/wireguard/1.0.20200611/build/receive.o
  CC [M] /var/lib/dkms/wireguard/1.0.20200611/build/socket.o
/var/lib/dkms/wireguard/1.0.20200611/build/socket.c: In function ‘send6’:
/var/lib/dkms/wireguard/1.0.20200611/build/socket.c:139:18: error: ‘const struct ipv6_stub’ has no member named ‘ipv6_dst_lookup_flow’
   dst = ipv6_stub->ipv6_dst_lookup_flow(sock_net(sock), sock, &fl,
                  ^
scripts/Makefile.build:277: recipe for target '/var/lib/dkms/wireguard/1.0.20200611/build/socket.o' failed
make[1]: *** [/var/lib/dkms/wireguard/1.0.20200611/build/socket.o] Error 1
Makefile:1437: recipe for target '_module_/var/lib/dkms/wireguard/1.0.20200611/build' failed
make: *** [_module_/var/lib/dkms/wireguard/1.0.20200611/build] Error 2