Do 25Us actually do their job in the National Guard? How do I go about progressing further in my career with 10-level skills as a fresh E5?

Unfortunately it is all too normal. But you can fix it.

Make contact with your Battalion S6 shop. Ask if they can provide training and resources. Coordinate it with your chain of command. Ask for permission to train with the S6 shop, say one a quarter or twice a year. Sell it with information on how this will improve your ability to keep equipment operational.

As a Servant you should have a mastery of most 10 level tasks and 20 level should be your focus and becoming exposed to 30 level when you get read for the next promotion.

Are you enrolled in DACAP? Are you the only one? If not, start training key players on COMSEC and get them enrolled so they can handle their own SKLs.

Advertise your expertise and hold training sessions for the platoon RTOs. Demand your chain give you the training time to do it and do it well. Not just operation, but proper procedure, COMSEC compromise, OTAR, JBC-P....

Start tracking your company's comms equipment readiness and report that up to BN each month. That S6 has to keep a running estimate of those numbers and the link between company and battalions always the worst, make yours the exception.

A lot depends on the unit. When I was assigned to a brigade HQ the network people were pulled after formation and did server/network stuff all weekend. When I deployed as a commo chief with an infantry battalion (HQ company) the commo section was additional manpower for the S-4 every time we turned around. Couldn't touch the scouts, everyone in the unit was their support. I've been retired about 10 years now so things may have changed.

Build a strong relationship with your Training NCO. Make sure they know you need classes. I go to the CPOF class and volunteer for classes all the time. I always help supply too but I always have my COMMO cage organized and I maintain my equipment. Verify how many services you have to complete on the equipment your signs for, whether that's quarterly or annually. I always teach classes to my unit. They always forget the basics since they only drill once a month. Remember that 10 level is for the operator.