# Cannot connect wifi problem \[RESOLVED\]
**URL:** https://community.particle.io/t/cannot-connect-wifi-problem-resolved/4259
**Category:** Troubleshooting
**Created:** [May 9, 2014, 1:28pm UTC](https://community.particle.io/t/cannot-connect-wifi-problem-resolved/4259 "2014-05-09T13:28:27Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@robin](https://community.particle.io/u/robin)
#### Post date: [May 9, 2014, 1:28pm UTC](https://community.particle.io/t/cannot-connect-wifi-problem-resolved/4259/1 "2014-05-09T13:28:27Z")
I just got the spark, but encountered a problem. I use spark command line `serial wifi`, follow the prompts to fill in the SSID and password are correct. but it keeps flashing green. Please help me!
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### Author:  [@zach](https://community.particle.io/u/zach)
#### Post date: [May 9, 2014, 1:36pm UTC](https://community.particle.io/t/cannot-connect-wifi-problem-resolved/4259/2 "2014-05-09T13:36:44Z")
Hi @robin,
Happy to help! Flashing green means that the Core is attempting to connect to Wi-Fi but unable to connect. Have you followed the troubleshooting guide?
[http://docs.spark.io/#/troubleshooting](http://docs.spark.io/#/troubleshooting)
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### Author:  [@robin](https://community.particle.io/u/robin)
#### Post date: [May 9, 2014, 1:57pm UTC](https://community.particle.io/t/cannot-connect-wifi-problem-resolved/4259/3 "2014-05-09T13:57:02Z")
I looked over the troubleshooting guide, factory reset of still not solved. i’m using core is u.FL connector, which referred `If your Core has a u.FL connector, you must connect an external antenna before initiating Smart Config` what is meant?
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### Author:  [@kennethlimcp](https://community.particle.io/u/kennethlimcp)
#### Post date: [May 9, 2014, 1:59pm UTC](https://community.particle.io/t/cannot-connect-wifi-problem-resolved/4259/4 "2014-05-09T13:59:19Z")
You require an external antenna for the u.fl version of the core.
If you do not use an antenna, connection might not work
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### Author:  [@zach](https://community.particle.io/u/zach)
#### Post date: [May 11, 2014, 1:08am UTC](https://community.particle.io/t/cannot-connect-wifi-problem-resolved/4259/5 "2014-05-11T01:08:25Z")
> [@robin](#):
>
> i'm using core is u.FL connector, which referred If your Core has a u.FL connector, you must connect an external antenna before initiating Smart Config what is meant?
Here is an explanation of the difference between the two antenna options:
[Kickstarter update](https://www.kickstarter.com/projects/sparkdevices/spark-core-wi-fi-for-everything-arduino-compatible/posts/534154)
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### Author:  [@robin](https://community.particle.io/u/robin)
#### Post date: [May 21, 2014, 2:02pm UTC](https://community.particle.io/t/cannot-connect-wifi-problem-resolved/4259/6 "2014-05-21T14:02:16Z")
Thanks for your reply, the problem has been resolved.[quote=“kennethlimcp, post:4, topic:4259, full:true”]
You require an external antenna for the u.fl version of the core.
If you do not use an antenna, connection might not work
[/quote]
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### Author:  [@robin](https://community.particle.io/u/robin)
#### Post date: [May 21, 2014, 2:06pm UTC](https://community.particle.io/t/cannot-connect-wifi-problem-resolved/4259/7 "2014-05-21T14:06:03Z")
Hi @zach , Thanks for your help! the problem has been resolved.