If neither your domain name provider nor your ISP can help you, really nobody can help.
Especially your domain name provider should know, that a HTTP redirect on an url is always fully transparent to the clients browser.
What you need is just an A Record which translates your doman name to your ip-address (without port!).
The port must be added to the domain name: http://example.com:81
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~free software according to purpose of usageXAMPP 1.8
for local development/testing onlyZend Server 6 (free)
for production environments
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