Here is the Servers Firewall status.
root@server3:/home/loren# ufw status
Status: active

To Action From
-- ------ ----
8080/tcp ALLOW Anywhere
26000:26030/tcp ALLOW Anywhere
26000:26030/udp ALLOW Anywhere
22/tcp ALLOW Anywhere
8080/tcp (v6) ALLOW Anywhere (v6)
26000:26030/tcp (v6) ALLOW Anywhere (v6)
26000:26030/udp (v6) ALLOW Anywhere (v6)
22/tcp (v6) ALLOW Anywhere (v6)

root@server3:/home/loren#

Here is a Screen shot of PFSense Firewall Nat Routing


In case the link doesn't show up here it is.
http://lorentedford.com/wp-content/uploads/2019/08/server-3-port-forwarding.png

Here is what the server is showing we are using Lgsm

Distro Details
===================================================================================================================================================
Distro: Ubuntu 18.04.3 LTS
Arch: x86_64
Kernel: 4.15.0-54-generic
Hostname: server3
tmux: tmux 2.6
glibc: 2.27

Performance
Uptime: 28d, 22h, 17m
Avg Load: 0.02, 0.04, 0.01

CPU Model: Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz
CPU Cores: 8
CPU Frequency: 800.015 MHz

Mem: total used free cached available
Physical: 16GB 1.2GB 15GB 11GB 15GB
Swap: 8.0GB 1.0MB 8.0GB

Storage
===================================================================================================================================================
Filesystem: /dev/sda2
Total: 219G
Used: 41G
Available: 167G
LinuxGSM Total: 4.8G
Serverfiles: 4.5G

Insurgency: Sandstorm Server Details
===================================================================================================================================================
Server name: GameTrackerClaimServer
Server IP: 10.10.10.135:26001
Internet IP: 157.185.79.38:26001
Server password: NOT SET
RCON enabled: NOT SET
RCON password: NOT SET
Maxplayers: 64
Default Map: Canyon
Default Scenario: Scenario_Crossing_Push_Security
Status: ONLINE

inssserver Script Details
===================================================================================================================================================
Service name: inssserver
inssserver version: v19.9.0
User: ins-sandstorm1
glibc required: 2.17
Discord alert: off
Email alert: off
Pushbullet alert: off
IFTTT alert: off
Mailgun (email) alert: off
Pushover alert: off
Telegram alert: off
Update on start: off
Location: /home/ins-sandstorm1
Config file: /home/ins-sandstorm1/serverfiles/Insurgency/Saved/Config/LinuxServer/Game.ini

Backups
===================================================================================================================================================
No Backups created

Ports
===================================================================================================================================================
Change ports by editing the parameters in:
/home/ins-sandstorm1/lgsm/config-lgsm/inssserver

Useful port diagnostic command:
netstat -atunp | grep Insurgency

DESCRIPTION DIRECTION PORT PROTOCOL
> Game INBOUND 26001 udp
> Query INBOUND 26000 udp
> RCON INBOUND 0 tcp

Status: ONLINE


But I still get the error that Game Tracker Can't see the server.

Server Just now finally registered no other changes were made however I posted a new bug issue with your site in regards of Verification failing..