I am assuming that the two drains are tied together since no other drain in the house is having issues.

For years we have been having issues with the shower drain backing up, but usually a good plunging takes care of it... wife sheds a fair amount so I have always just attributed the issue to her hair. Few months ago we got a new washing machine and the backing up has gotten more frequent, and it now includes backing up of the washing machine drain. Ive snaked the drain from the washing machine, no dice... never seemed to get anything.

At a loss as to what to do, or where the problem could be.

If these fixtures are on a slab or in the basement then I suspect that you may have a PARTIAL BLOCKAGE of the main drain line. Here, remove the cleanout from the main drain where it exits the building and then run the washing machine. If water backs up and out the cleanout then the main drain is partially clogged and will need to be snaked to clear the drain.

Back to you...

Mark

It's a pretty bad idea to have a washer and a shower of the same drain. Especially if the washer is upstream from the shower. If no other fixtures cause a backup then in my opinion the main drain is clear. Mark is correct when he says that you have a partial blockage. However, I believe it is local and not in the line to the Street. Are there any cleanouts on the vertical stacks? If not, you could address the blockage from the shower drain all the washer standpipe. Good luck, Tom

You have a partial stoppage in the line, sounds like you did not have enough cable in the line to reach it. If you have more cable then try it again, otherwise call a plumber to clear it.

Ive snaked the drain from the washing machine, no dice... never seemed to get anything.
Removed the shower strainer and snake the line from there. If that don't work click on back and will go to plan "B". Good luck, Tom