is there a way to give a lan port priority over other lan ports for internet access?
This is not possible, all LAN ports have the same priority. What do you need to accomplish, can you provide more details?
the customer has 4 dsl modems and they go to a wifi system for the property and then another router off the peplink between the customer and there lan. I want to give priority to there data traffic over the customer traffic to the internet.
For your information, start with firmware version 6.2.1 group bandwidth reservation feature are available for Balance 50. You may consider to use this feature to limit the available upload/download speeds for the IP/Subnet in the LAN.
For more information, you may refer to the attached screenshots:
User Group Settings
Group Bandwidth Control Settings
Else, if this is not the feature that you looking at, do provide more info for your current network setup for us to advice accordingly.