heroku.com is an external service in the Internet. You don't need to configure your home router to be able to access it.
Port forwarding is used when you want other locations to be able to connect to servers in your home. You don't need to use port-forwarding to connect to any Internet server regardless of the port number.
For diagnosis try
ping s1.runtime.heroku.com
You should see
C:\>ping s1.runtime.heroku.com
Pinging ec2-107-20-246-116.compute-1.amazonaws.com [107.20.246.116] with 32 bytes of data:
Reply from 107.20.246.116: bytes=32 time=116ms TTL=52
Reply from 107.20.246.116: bytes=32 time=116ms TTL=52
Reply from 107.20.246.116: bytes=32 time=116ms TTL=52
Reply from 107.20.246.116: bytes=32 time=116ms TTL=52
Ping statistics for 107.20.246.116:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 116ms, Maximum = 116ms, Average = 116ms
If ping doesn't succeed, you can check where the problem lies using tracert
C:\>tracert s1.runtime.heroku.com
Tracing route to ec2-107-20-246-116.compute-1.amazonaws.com [107.20.246.116]
over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms your_local_home_router_name
2 37 ms 35 ms 36 ms your_isp_router_name
3 36 ms 35 ms 35 ms a_router_in_your_isp_network
4 36 ms 37 ms 37 ms a_different_router_in_your_isp_network
5 120 ms 118 ms 117 ms some_other_network_company_router
6 116 ms 115 ms 115 ms foo
7 115 ms 115 ms 116 ms bar
8 121 ms 118 ms 119 ms elsewhere
9 116 ms 117 ms 117 ms someplace
10 * * * Request timed out.
11 * * * Request timed out.
12 * * * Request timed out.
13 * * * Request timed out.
14 * * * Request timed out.
15 118 ms 115 ms 116 ms ec2-107-20-246-116.compute-1.amazonaws.com [107.20.246.116]
Trace complete.
The "Request timed out" lines just indicate a router that doesn't respond to route-tracing requests for security reasons. The final line indicates we reached the heroku service (which uses Amazon infrastructure)