While you were just a child, you've probably had a chance to spend a lot of time with your grandparents. They were like a second pair of parents since your mom and dad were busy with providing for the family. Once you got older and independent, you started choosing your company and maybe neglected your grandparents. They've got older, and it's not that easy to connect with them now. Modern technology also played its role in this separation since they weren't ready to learn new things and operate smart devices. Whatever caused the distance between you, it's not too late to reconnect once again.
Learn about their interests
This piece of advice was presented in Carnegie's classic "How to wind friends and influence people", and it's still working today. Use the knowledge about your grandparent's interests as a starting point and build your relationships from there. It would be great if they have some hobbies so you can spend some time doing it with them. Your parents might be in love with the outdoors, so you can take a walk with them, or help them prepare their favorite meal during the weekends. These activities can serve you good especially if your hobbies are tightly connected to technology.
There are so much you can learn from your grandparents and much more you can teach them. As suggested above, seniors are not as good with technology as you are and maybe you should invest some time in teaching them how to search the internet in order to find recipes for their favorite meals or book a ticket for a theater. On the other hand, your grandad can teach you some woodworking, or you can earn knitting skills from your grandmom. They'll be happy to share and probably to learn new things, so give this a try.
Send them a letter
If you have a lot of responsibilities on weekdays, and you're unable to visit your grandparents, it would be great if you'd send them an occasional handwritten letter or a card. They would like to know what is happening in your life, and the best way to communicate with them is via paper and pen. They will be happy if you just give them a call, but the letter will make them think about their youth when that was the only way of communication with loved ones. Your simple gesture will help them to travel in the past and enjoy their memories.
Help them renovate their home
In order to maintain a healthy relationship with your grandparents, you'll need to be there when they need help. Their house may be a little old and filled with outdated appliances, so you can offer them your help with the renovation. They would be glad to accept your help, especially for lifting heavy items. Do everything you can, and if you're unable to complete some tasks, feel free to seek help from professional senior living architects. They will make your grandparents' place much better, and your folks will be happy and filled with fresh energy.
As you can see, you can do so much for your grandparents by doing really little. Try to be patient with them and answer all their needs and questions. They'll know to appreciate that, so you'll feel much better about yourself. Spend some time with them while they're in good health, and be close once they got really old. If you manage to understand them, your grandchildren will be able to understand you in the future.