Hi Manacore24,
Try this one below. Make sure you delete any existing apn before you enter and save this one as the default also turn off and restart the phone after saving it.
I would suggest writing down your current internet apn if it is currently working just in case this doesn't work so you can at least get that back.
Internet APN
Setting Value
Profile Name Straight Talk
APN tfdata
User Name <blank>
Password <blank>
Type of sign-in info None
IP Type IPv4v6
Use this APN for LTE Checked
Proxy Server <blank>
Proxy Port <blank>
MMS APN
Setting Value
Profile Name Straight Talk
APN tfdata
User Name <blank>
Password <blank>
Type of sign-in info None
IP Type IPv4v6
Proxy Server mms3.tracfone.com
Proxy Port 80
MMSC (URL)
http://mmsc.cingular.com/
MMSC Port 80
Maximum MMS Size <blank>
Possibly instead of this line MMSC (URL)
http://mmsc.cingular.com/
you can try
http://mms-tf.net in place of it.
All of the above settings is only if your phone is on the AT&T side of Straight Talk. If its on the Tmobile side that is completely different apn.
Good Luck,
Willdb