Is that through your service providers website? If so then make sure your internal IP is your devices IP. To get it, do windows key + r, then type in cmd. the command prompt should open up and then type in ipconfig. Look for your IPv4 address and replace 192.168.0.145 with the IPv4. If it's already your device's IP, then I'm not entirely sure what's wrong.
Since I'm not able to port Forward, i had to use an alternative solution. My solution was:
1. Open file explorer
2. go to network (you might have to enable a setting to see what devices are on the network)
3. find your wifi routers name (Usually under Network Infrastructure)
4. right-click your router and go to properties
5. there should be 2 tabs, a general tab and network device tab. click the general tab.
6. click settings in the general tab.
7. advanced settings should pop up, then press add...
8. a window should pop up, Service settings.
Description of Service: srb2
Name or IP: (your device IP)
External port number for this service: 5029
Internal port number for this service: 5029
have TCP checked, then click OK
Then go to this
website and go to method 2.
This might not help at all, but these are solutions for people that can't port forward their router.
Ask for help if you need any!