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5053 is the RLM's default port. So, if you are using a RLM-licensed software already then port 5053 is already in use. The solution is to edit your license file. There, you will find a line indicating the used port. for example
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Change “5053” to something like 5052, or 5060, but do not use 5054, because this port is required occupied by the RLM's web interface.
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