Hello & Welcome to Just Answer,
I'm Greg and will do my best to assist you today.
Sorry to hear of any issue you are having with your phones.
To help you with this issue, may I ask:
1) Can you CONFIRM the FULL Model Number of the phone system you are working with? I only ask because it looks like there may be an extra letter or number in the model you sent (KX-TGF 3400).
2) How many TOTAL cordless handsets do you have with this system?
Please REPLY using the box below and the SEND button.
Hi again and thanks for that information.
OK - I have a couple of resources for you.
First is a link to the FULL manual for this system - in electronic (PDF) form. If you are using a computer to receive these messages, clicking the link SHOULD display the manual on the screen, or perhaps download the manual.
If you are using a "smartphone" to look at these messages, the manual MAY or MAY NOT display, depending on if you have a PDF viewing application installed on the phone.
Next, I have also attached an image with the instructions (from the manual) about how to set the date and time. You MAY have to click on the attachment NAME to see the image.
Lastly, I have a link to a Video that shows how to set the date and time on this and similar systems - using one of the handsets.
Again, if reading this information on a smartphone, the video MAY or MAY NOT play, depending on if you have a compatible video player application installed on the phone.
If viewing this on a computer, the video should play in the browser.
Click Here for Video --> https://www.youtube.com/watch?v=AUwQ0N4eCfw
Please try one or more of these resources to attempt to set the date and time, and let me know your results - when you can.
If this has helped answer your question(s), please take a moment to rate MY service level (5-star is my goal) so that I get credit for my time helping you with this question.You should see some "stars" (and SUBMIT button) to do that, but please let me know if you do NOT see them (you may have to REFRESH your screen) or can not use them.
Thanks, ***** *****--. .-