[FEAT] Add section to troubleshooting regarding ISP blocking.

[AwkwardGecko]

Is this a new feature request?

• I have searched the existing issues

Wanted change

https://docs.linuxserver.io/general/swag/#troubleshooting

I think the troubleshooting section could include a line about time-out errors being a result of ISP blocking ports.

Reason for change

I've been bashing my head against a wall for the last week trying to access my server remotely. Turns out all I needed to do was log into my ISP portal and deactivate the security feature to block ports.

I understand this might be regarded as fairly obvious to people in this space, but as a newcomer to the self-hosting community, having this spelled out would have saved me a lot of time and frustration.

Proposed code change

No response

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