First isolate what causes the problem. You can connect directly to the modem. If issue is the same call your Internet Service Provider.
If if works perfectly when connected directly to the modem then you just ruled out an Modem or ISP concern. Then you might want to update the firmware of your router. To do that safely, please contact linksys. I am aware that every model number has different model numbers thus they have different firmware updates.
Thank you very much!