If not able to solve, then just read too many solutions without wasting too much time on thinking them. They follow some common patterns. You will get it after reading a lot of them.

I feel like telling yourself that you don't have the capability to do harder problems limits you quite heavily. Take a silly example, if you look at 1098B - Nice table and 435E - Special Graph, they are almost the same. Yet one of them has rating 2100 and the other one has rating 2500. So I'd say if you can do 2100 problems, then you should also have the capability to do some problems with much higher rating. But if you just tell yourself that you can't do hard problems, then if you happened to look at the version of that problem with rating 2500, you will just not try and not know that you can potentially do it.

I think just saying "I can't solve anything higher than that" is kind of dumb. Even me as a noob have managed to do some hard problems on my own recently. Come on, you are definitely better than me :P

There are many "I'm stuck on some level" blogs in CF, just go read them. If you're stuck for a year then likely there's something wrong with your practice method or you just hit your max possible level ever. Useful links about getting 2400+ and "science" of training: https://codeforces.com/blog/entry/66909 https://codeforces.com/blog/entry/17842 https://github.com/Errichto/youtube/wiki/How-to-practice%3F