RCON refuses to connect to Vultr Server - Team Fortress 2 server

I made a server for TF2 on a Vultr instance, running Ubuntu 18.04.2 LTS.

Everything went well, except that when I try running the RCON commands, it hits me with this error:

Unable to connect to remote server (my.server.ip.here:27015)

I followed the instructions here.

What am I doing wrong? Is there a specific config I need for Vultr?

My server.cfg:

// General Settings //

hostname TF2 Server - DNJ
sv_contact [REDACTED]
sv_lan 0            // Server type; 0 = Internet; 1 = LAN
sv_region -1            // Region: -1 = World; 0 = USA East; 1 = USA West; 2 = S. America;
                                // 3 = Europe; 4 = Asia; 5 = Australia; 6 = Middle East; 7 = Africa

// Passwords //

rcon_password [REDACTED]        // Password for administrator access
sv_password         // Server password


// Server Logs //

log on
sv_logecho 1            // Echo log information into your console
sv_logfile 1            // Add log file
sv_log_onefile 0        // Log to a single file
sv_stats 1          // Collect CPU usage states


// Bans and Ban Logs //

sv_rcon_maxfailures 5       // Max amount of failed RCON logins before ban (between 1 - 20)
sv_rcon_banpenalty 60       // Ban time for RCON failed login in minutes
sv_logbans 1            // Turn on ban logging


// Server Downloads/Uploads //

sv_allowdownload 1
sv_allowupload 1
sv_consistency 1        // File consistency check
net_maxfilesize 15      // Max file size for uploading in MB


// Pure Server //
// Pure Servers force all clients to use content that matches the server

sv_pure 2           // 0 = Off; 1 = Enforce via pure_server_whitelist.txt
                                // 2 = Steam official content
sv_pure_kick_clients 1      // Kick clients in violation
sv_pure_trace 1         // Display violation message


// Bandwidth & Frame Rates //

sv_maxrate 50000        // Max bandwidth rate; 0 = Unlimited
sv_minrate 0            // Min bandwidth rate; 0 = Unlimited
sv_maxupdaterate 66         // Max updates per second
sv_minupdaterate 10     // Min updates per second
fps_max 600             // Frame Rates; 0 = Unlimited


// Server Variables //

mp_allowspectators 1
sv_cheats 0
sv_pausable 0
mp_footsteps 1
sv_allow_votes 1        // Vote on maps
mp_forcecamera 1        // Camera restriction for dead players
mp_idlemaxtime 3        // Max idle time for players (in minutes)
mp_idledealmethod 1         // Idle player kick method; 0 = Off; 1 = Move to spectate; 2 = Boot


// Game Variables //

sv_visiblemaxplayers 24     //Max players
mp_friendlyfire 1
mp_flashlight 1
mp_falldamage 0
tf_weapon_criticals 1       // Allows crits
tf_damage_disablespread 0   // Random damage spread (±10%)
tf_use_fixed_weaponspreads 0    // Consistent spread for weapons


// Team Autobalance //

mp_autoteambalance 1
mp_teams_unbalance_limit 2  // Amount of additional players on team before unbalanced


// Round Variables //

mp_enableroundwaittime 1    // Enables timers between rounds (setting this to 0 causes a known bug)
mp_bonusroundtime 15        // Time after win until restart
mp_restartround 0       // Round restart in seconds
mp_stalemate_enable 0       // Enable sudden death
mp_stalemate_timelimit 240  // Timelimit of stalemate round
mp_maxrounds 0          // Max rounds before map change
mp_winlimit 0           // Max wins before map change
mp_timelimit 0          // Max time before map change


// Communication //

sv_voiceenable 1
sv_alltalk 0            // Players can hear all other players
mp_chattime 10          // Post-game chat in seconds


// Execute ban files //

exec banned_user.cfg
exec banned_ip.cfg
writeid
writeip

My startup script (tf.sh)

#!/bin/sh
screen -S "TF2" tf2/srcds_run -console -game tf +sv_pure 0 +ip 0.0.0.0 +map ctf_2fort +maxplayers 24