Nginx backend to one of 4 hosts in Docker Swarm - nginx

Question

I've been searching around and haven't found a solution to my situation. I'm running a cluster of 5 machines with Docker Swarm. For right now, I'm trying to get two of the containers communicating with each other. If both containers are running on the same single machine, everything works fine. If one container is on one machine/node, and another container is on a different machine/node, things stop working.
One container is nginx, the other is a front-end nodejs app that nginx will act as a proxy for. nginx "assumes" that the front-end container is running on the localhost only. Although this can be the case, it's not always the case. The front-end container can be running in one of any 5 hosts.
I'm not sure how to get nginx to realize that there are 4 other hosts out there which might have this front-end service it needs to connect with. I do have a DNS on IP 127.0.0.11 (Docker standard embedded DNS server).
Here is an error I see whenever the containers are on different nodes
2016/11/01 14:33:41 [error] 8#8: *1 connect() failed (113: No route to host) while connecting to upstream, client: 10.255.0.3, server: , request: "GET / HTTP/1.1", upstream: "http://10.10.0.2:8079/", host: "cluster3"
In this case, cluster3 is the localhost running the nginx container. However, front-end is running on cluster4, which explains why it can't find front-end.
Below is my current nginx.conf file. Is there something I can change here to get this to work right? I was playing around with upstream and resolver but that didn't seem make a difference.
worker_processes 5; ## Default: 1
worker_rlimit_nofile 8192;
events {
worker_connections 4096; ## Default: 1024
}
http {
server { # simple load balancing
listen 80;
location / {
proxy_pass http://front-end:8079;
}
}
}
EDIT:
I notice the following gets printed to the kernel logs whenever I point my browser to the nginx instance.
[ 225.521382] BUG: using smp_processor_id() in preemptible [00000000] code: nginx/3501
[ 225.528808] caller is $x+0x5ac/0x828 [ip_vs]
[ 225.528820] CPU: 0 PID: 3501 Comm: nginx Not tainted 3.14.79-92 #1
[ 225.528825] Call trace:
[ 225.528836] [<ffffffc001088e40>] dump_backtrace+0x0/0x128
[ 225.528842] [<ffffffc001088f8c>] show_stack+0x24/0x30
[ 225.528849] [<ffffffc00188460c>] dump_stack+0x88/0xac
[ 225.528858] [<ffffffc0013dcf94>] debug_smp_processor_id+0xe4/0xe8
[ 225.528899] [<ffffffbffc1ec8fc>] $x+0x5ac/0x828 [ip_vs]
[ 225.528938] [<ffffffbffc1ecbdc>] ip_vs_local_request4+0x2c/0x38 [ip_vs]
[ 225.528945] [<ffffffc001789ecc>] nf_iterate+0xc4/0xd8
[ 225.528951] [<ffffffc001789f6c>] nf_hook_slow+0x8c/0x138
[ 225.528957] [<ffffffc0017994e8>] __ip_local_out+0x90/0xb0
[ 225.528963] [<ffffffc001799528>] ip_local_out+0x20/0x48
[ 225.528968] [<ffffffc001799848>] ip_queue_xmit+0x118/0x370
[ 225.528975] [<ffffffc0017b09d8>] tcp_transmit_skb+0x438/0x8b0
[ 225.528980] [<ffffffc0017b231c>] tcp_connect+0x54c/0x638
[ 225.528987] [<ffffffc0017b50c8>] tcp_v4_connect+0x258/0x3b8
[ 225.528993] [<ffffffc0017cca50>] __inet_stream_connect+0x120/0x358
[ 225.528999] [<ffffffc0017cccd0>] inet_stream_connect+0x48/0x68
[ 225.529005] [<ffffffc00173bf80>] SyS_connect+0xc0/0xe8
[ 269.026442] BUG: using smp_processor_id() in preemptible [00000000] code: nginx/3501
[ 269.028592] caller is ip_vs_schedule+0x31c/0x4f8 [ip_vs]
[ 269.028600] CPU: 0 PID: 3501 Comm: nginx Not tainted 3.14.79-92 #1
[ 269.028604] Call trace:
[ 269.028618] [<ffffffc001088e40>] dump_backtrace+0x0/0x128
[ 269.028624] [<ffffffc001088f8c>] show_stack+0x24/0x30
[ 269.028632] [<ffffffc00188460c>] dump_stack+0x88/0xac
[ 269.028641] [<ffffffc0013dcf94>] debug_smp_processor_id+0xe4/0xe8
[ 269.028680] [<ffffffbffc1eb2dc>] ip_vs_schedule+0x31c/0x4f8 [ip_vs]
[ 269.028719] [<ffffffbffc1fe658>] $x+0x130/0x278 [ip_vs]
[ 269.028757] [<ffffffbffc1eca08>] $x+0x6b8/0x828 [ip_vs]
[ 269.028795] [<ffffffbffc1ecbdc>] ip_vs_local_request4+0x2c/0x38 [ip_vs]
[ 269.028802] [<ffffffc001789ecc>] nf_iterate+0xc4/0xd8
[ 269.028807] [<ffffffc001789f6c>] nf_hook_slow+0x8c/0x138
[ 269.028814] [<ffffffc0017994e8>] __ip_local_out+0x90/0xb0
[ 269.028820] [<ffffffc001799528>] ip_local_out+0x20/0x48
[ 269.028825] [<ffffffc001799848>] ip_queue_xmit+0x118/0x370
[ 269.028832] [<ffffffc0017b09d8>] tcp_transmit_skb+0x438/0x8b0
[ 269.028837] [<ffffffc0017b231c>] tcp_connect+0x54c/0x638
[ 269.028844] [<ffffffc0017b50c8>] tcp_v4_connect+0x258/0x3b8
[ 269.028850] [<ffffffc0017cca50>] __inet_stream_connect+0x120/0x358
[ 269.028855] [<ffffffc0017cccd0>] inet_stream_connect+0x48/0x68
[ 269.028862] [<ffffffc00173bf80>] SyS_connect+0xc0/0xe8