I feel like I somehow got into a narrow minded patching routine, not being able to think outside the box, or to take it to a higher level, being stuck with basic techniques I learned in the beginning.. I know there are no real shortcuts in learning any skill, but I also know that there are good and bad ways in learning any skill...
Has anyone felt like this, do you have any good and real advice?
Thanks in advance :)

You can always set little goals:

Only use Noise: filter it, sweep it, gate it, lower the volume through a VCA and something like a ADDAC103 and you get some lovely sweep-able crackle, with an envelope follower after that you can run your whole system clicking from noise crackle. You can combine Noise with low VCO and LFO like @Anthuriumsounds on Youtube does and there is a walk through of how they do it.

Always Unpatch everything: I'm bad at not doing this but it helps make you try different things, I was getting stuck leaving all my percussion section patched up.

Try some Feedback loops: You can use a simple Mixer or Attenuator to limit and control the feedback.

Single VCO: try splitting different waveforms off into different effects (Everything will be in tune), something like the MakeNoise STO is great for this with its S-Gate you can easily make a good piece from just the STO.

Use a Pitch sequence to control a filter rather than a VCO.

Use random snippets of gated audio as percussion.

Use different length Euclidean patterns to liven-up your percussion so they evolve over a longer timeframe.

Add a gate sequence AFTER your effects or add it both before and after the effects.

Thats a few things I've played with, hope it gives you some ideas or something you haven't thought of.

You can try arranging your modules differently or changing your modules altogether.

Take only a few modules and start making music with them.
(try to take it to new/other directions, if necessary read manuals)
Narrowing down to a very small setup teaches me a lot every time. The music that comes out is mainly shit, but the things I learn I can use in a bigger setup again.

I second everything @wishbonebrewery said. All great advice.
I unpatch almost everything every time I sit down to play. I have just a few "normalled" connections, but mostly start from scratch. I've tried to eliminate modules that don't encourage experimentation, or get in the way of creativity. Along the way, I've also gotten stuck in ruts but after watching some demo videos or trying to recreate a sound someone else has recorded (especially Autechre, holy cow.) I've had a few epiphanies about new ways to utilize what I do have. If you have a very small setup, you will be limited, so maybe have a few modules on standby to switch in and out for inspiration.
Above all, try to make it fun. If you are stuck, just experiment and make some crazy noise for a while. You might surprise yourself with a cool new tone.

write a patch randomiser script/program - if you search around the internet then there's an example written in Python by Daniel Cramer which should be easy to find, understand and modify - it was written for a small portable system, but can be scaled to any size - there are some "features" of it which could be improved, but it's a good starting point

"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia

Utility modules are the dull polish that makes the shiny modules actually shine!!!

sound sources < sound modifiers < modulation sources < utilities

One thing that I find helpful is to create a set of rules, instructions and restrictions and then randomly choose one before beginning a patch. You can sit down, write out a list, number each, then use a random number generator online to select one (or you could create a set of cards with 1 rule on each card, then just pick a card).

I find that doing this I've created many interesting patches that I would not have created otherwise.

I actually created an Excel worksheet with all these rules and use the random function to generate new rules each time I feel stuck or just feel like trying something new. I put together about 60 possible rules (examples: use filtered noise as a sound source, use a function generator, modulate a vca with a slow changing CV, use 2 different utility modules, , etc., etc...) .

I even have the worksheet randomly generate the cable combo to start my patch with (example: start with 4 long, 2 short and 3 medium cables).

I also always remove all cables when done so I start from scratch each day I use my synth.

Start from a blank patch, nothing patched. Then patch your initial idea: what do you want to try or learn, what module do you want to explore? This could be something obvious like a basic technique, it could also be something complex or abstract. Stay with that initial thought.
When you think you're finished, record the patch, power off your system and unplug everything. Next session: do the same. Not only will you be able to learn your system better, you'll also have a collection of your own recordings.

My music on Bandcamp - Instagram - YouTube

In case my opinion may be useful, six months ago I started with modular hardware. I have started with a very tight budget, and acquiring modules for a "basic" patch (VCO, filter, VCA's, basic Envelopes).
After many "patch and unpatch" I think that, although the basic utilities (VCA's, LFO's, envelopes) are essential, but more complex modules are the ones that give more room for experimentation. Mainly effects (delay, distortion), waveshapers and filters with some extra function.
I think that now I have entered a second phase, where I am exploring for example my Endorphin.es Airstreamer and my NE Viol Ruina filter and although they are quite basic modules, it is surprising what they give of themselves.

There is somewhere a pdf "The book of bad ideas" not sure if it was on this forum, i dont want to look for the link now.

Also watch lots of videos, i would suggest Make Noise, Monotrail, Undulations (allthough he does not mainly Eurorack but definitely helps you to think out of the box like clocking a sequencer with an audio signal from playing piano or clocking it at audio rate and using as audio source and gazillions of other weird ideas of abusing stuff)

There is somewhere a pdf "The book of bad ideas" not sure if it was on this forum, i dont want to look for the link now.