Trouble Accessing Remote Neo4j Server

I installed neo4j on a remote Ubuntu 18.04 Digital Ocean droplet. When I check the status of my neo4j server I see that my server is actively running and the remote interface is available at port 7474

username@ip-***-**-**-***:~$ sudo service neo4j status
neo4j.service - Neo4j Graph Database  
 Loaded: loaded (/lib/systemd/system/neo4j.service; disabled; vendor preset: enabled)   
Active: active (running) since Mon 2019-11-25 18:21:05 UTC; 1min 8s ago 
Main PID: 11340 (java)    
Tasks: 40 (limit: 2362)   
CGroup: /system.slice/neo4j.service           
└─11340 /usr/bin/java -cp /var/lib/neo4j/plugins:/etc/neo4j:/usr/share/neo4j/lib/*:/var/lib/neo4j/plugins/* -server -XX:+UseG1GC -XX:-OmitStackTraceInFastThrow 
Nov 25 18:21:05 ip-***-**-**-*** neo4j[11340]:   import:       /var/lib/neo4j/import
Nov 25 18:21:05 ip-***-**-**-*** neo4j[11340]:   data:         /var/lib/neo4j/data
Nov 25 18:21:05 ip-***-**-**-*** neo4j[11340]:   certificates: /var/lib/neo4j/certificates
Nov 25 18:21:05 ip-***-**-**-*** neo4j[11340]:   run:          /var/run/neo4j
Nov 25 18:21:05 ip-***-**-**-*** neo4j[11340]: Starting Neo4j.
Nov 25 18:21:07 ip-***-**-**-*** neo4j[11340]: 2019-11-25 18:21:07.507+0000 INFO  ======== Neo4j 3.5.12 ========
Nov 25 18:21:07 ip-***-**-**-*** neo4j[11340]: 2019-11-25 18:21:07.528+0000 INFO  Starting...
Nov 25 18:21:11 ip-***-**-**-*** neo4j[11340]: 2019-11-25 18:21:11.566+0000 INFO  Bolt enabled on 0.0.0.0:7687.
Nov 25 18:21:14 ip-***-**-**-*** neo4j[11340]: 2019-11-25 18:21:14.347+0000 INFO  Started.
Nov 25 18:21:16 ip-***-**-**-*** neo4j[11340]: 2019-11-25 18:21:16.132+0000 INFO  Remote interface available at http://localhost:7474/

My firewall is enabled and allowing HTTP and OpenSSH access:

username@ip-***-**-**-***:~$ sudo ufw status
Status: active
To                         Action      From
--                         ------      ----
OpenSSH                    ALLOW       Anywhere                  
Nginx HTTP                 ALLOW       Anywhere                  
OpenSSH (v6)               ALLOW       Anywhere (v6)             
Nginx HTTP (v6)            ALLOW       Anywhere (v6) 

I made sure that I edited Neo4j's configuration file at /etc/neo4j/neo4j.conf and made the single edit to the file uncommenting the following line:

dbms.connectors.default_listen_address=0.0.0.0

After uncommenting that line I save the file and restart Neo4j

sudo service neo4j restart

When I go to http://SERVER_IP_ADDRESS:7474/browser/ on my laptop it just loads forever until landing on Firefox's default "Problem loading page". I have no idea what I'm doing wrong. I have searched far and wide across these forums and Google and haven't been able to solve this. I've come across this problem in other posts, but none of the solutions worked.

For the record, here is the Java software I installed on Ubuntu:

username@ip-***-**-**-***:~$ java -version
openjdk version "1.8.0_222"
OpenJDK Runtime Environment (build 1.8.0_222-8u222-b10-1ubuntu1~18.04.1-b10)
OpenJDK 64-Bit Server VM (build 25.222-b10, mixed mode)

For remote access you need to open ports 7474 (or 7473 for https) and 7687 for bolt. So try

sudo ufw allow 7474/tcp
sudo ufw allow 7687/tcp

I don't have HTTPS set up at the moment. Unfortunately, it's still not working. Below is the firewall status after making the changes you suggested.

username@ip-***-**-**-***:~$ sudo ufw status
Status: active
To                         Action      From
--                         ------      ----
OpenSSH                    ALLOW       Anywhere                  
Nginx HTTP                 ALLOW       Anywhere                 
7474/tcp                   ALLOW       Anywhere                  
7687/tcp                   ALLOW       Anywhere                  
OpenSSH (v6)               ALLOW       Anywhere (v6)             
Nginx HTTP (v6)            ALLOW       Anywhere (v6)             
7474/tcp (v6)              ALLOW       Anywhere (v6)             
7687/tcp (v6)              ALLOW       Anywhere (v6)    

what do you get upon netstat -atnp | grep LISTEN ?

Here you go:

username@ip-***-**-**-***:~$ sudo netstat -atnp | grep LISTEN 
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      916/nginx: master p 
tcp        0      0 127.0.0.53:53           0.0.0.0:*               LISTEN      700/systemd-resolve 
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      895/sshd            
tcp6       0      0 :::7687                 :::*                    LISTEN      1816/java           
tcp6       0      0 :::80                   :::*                    LISTEN      916/nginx: master p 
tcp6       0      0 :::7473                 :::*                    LISTEN      1816/java          
tcp6       0      0 :::7474                 :::*                    LISTEN      1816/java           
tcp6       0      0 :::22                   :::*                    LISTEN      895/sshd 

There it is: Neo4j uses ipv6 only. You can force it to use ipv4 instead. Add to your neo4j.conf the following line:

dbms.jvm.additional=-Djava.net.preferIPv4Stack=true