Heroku Hobby Dyno: Error in connection establishment: net::ERR_SSL_PROTOCOL_ERROR, server verification OK but ALPN server does not agree to protocol - ssl

Question

I have a simple app where the client is sending a request to join a websocket channel upon page load via a wss connection. I have deployed my app to heroku at domain my_app.heroku.com. Whenever I open my site, I get the error Error in connection establishment: net::ERR_SSL_PROTOCOL_ERROR. I understand that this is an SSL issue, and also that to use Heroku's SSL, you must be on a hobbyist account. So, I upgraded the app to hobbyist (one day ago), but it has not fixed the problem.
I have googled the issue, and from what I see it appears that additional setup beyond upgrading to Heroku Hobby should only be required if using a custom domain-name, which I am not. How can I get the SSL working on my my_app.heroku.com domain with the Hobby dyno?
EDIT: If I run curl -vI <my_app>.heroku_app.com I get the following:
curl -vI https://<my_app>.herokuapp.com
* Rebuilt URL to: https://<my_app>.herokuapp.com/
* Trying __.___.___.___...
* Connected to <my_app>.herokuapp.com (__.___.___.___) port 443
(#0)
* found 148 certificates in /etc/ssl/certs/ca-certificates.crt
* found 592 certificates in /etc/ssl/certs
* ALPN, offering http/1.1
* SSL connection using TLS1.2 / ECDHE_RSA_AES_128_GCM_SHA256
* server certificate verification OK
* server certificate status verification SKIPPED
* common name: *.herokuapp.com (matched)
* server certificate expiration date OK
* server certificate activation date OK
* certificate public key: RSA
* certificate version: #3
* subject: C=US,ST=California,L=San Francisco,O=Heroku\, Inc.,CN=*.herokuapp.com
* start date: Wed, 19 Apr 2017 00:00:00 GMT
* expire date: Mon, 22 Jun 2020 12:00:00 GMT
* issuer: C=US,O=DigiCert Inc,OU=www.digicert.com,CN=DigiCert SHA2
High Assurance Server CA
* compression: NULL
* ALPN, server did not agree to a protocol
> HEAD / HTTP/1.1
> Host: <my_app>.herokuapp.com
> User-Agent: curl/7.47.0
> Accept: */*
>
< HTTP/1.1 200 OK
HTTP/1.1 200 OK
< Server: Cowboy
Server: Cowboy
< Connection: keep-alive
Connection: keep-alive
< Content-Type: text/html; charset=utf-8
Content-Type: text/html; charset=utf-8
< Content-Length: 1154
Content-Length: 1154
< Date: Thu, 22 Nov 2018 08:39:51 GMT
Date: Thu, 22 Nov 2018 08:39:51 GMT
< Via: 1.1 vegur
Via: 1.1 vegur

Answer 1

I found the answer after finally finding this question. I thought all along the issue was due to setting up SSL certificates on Heroku, however it was due to my client side code. Per the tutorial I was following, the WS connection was "wss://my_app.herokuapp.com:80/subscribe". Removing the port number was the fix.