# Modbus TCP IP Server: Unable to connect to FIO Server via Modbus TCP Client PLC

**URL:** <https://community.factoryio.com/t/modbus-tcp-ip-server-unable-to-connect-to-fio-server-via-modbus-tcp-client-plc/1358>\
**Category:** Uncategorized\
**Created:** [March 7, 2022, 10:52am UTC](https://community.factoryio.com/t/modbus-tcp-ip-server-unable-to-connect-to-fio-server-via-modbus-tcp-client-plc/1358 "2022-03-07T10:52:28Z")\
**Posts on this page:** 1\
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**Author:** ![goncalo](https://avatars.discourse-cdn.com/v4/letter/g/3be4f8/32.png) [@goncalo](https://community.factoryio.com/u/goncalo)\
**Post date:** [March 8, 2022, 10:32am UTC](https://community.factoryio.com/t/modbus-tcp-ip-server-unable-to-connect-to-fio-server-via-modbus-tcp-client-plc/1358/2 "2022-03-08T10:32:30Z")

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> [@Driver Modbus TCP/IP Server](https://community.factoryio.com/t/driver-modbus-tcp-ip-server/262/3):
>
> Please make sure that inbound TCP connections at port 502 (the default Modbus server port) are allowed for Factory IO by any firewall running on the computer. For Windows Firewall, [here is a similar guide](https://docs.microsoft.com/en-us/sql/reporting-services/report-server/configure-a-firewall-for-report-server-access?view=sql-server-ver15#opening-ports-in-windows-firewall) on how to do it.

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