How to bump up endurance?

I've been off and on training since I was 16, I am almost 23 now. I'm not too close to my fitness goals, weighing in at 170/5 at 5'11 when I'd like to be 185. I hit it hard over a year ago with the power/hypertrophy plan by layne norton for three solid months, but I fell off the wagon after relocating for work and no access to a gym. I've been trying to get back to that mode of progress for a while now but I repeatedly find myself lacking endurance to pump out those last few crucial reps that signify lactic threshold, which I believe is just causing me to waste a lot of time. For hypertrophy days I will use a weight and get to the 10th rep with solid form but then I suddenly can't lift anymore, as if my muscle just doesn't want to move but I am not experiencing any type of burn. This happens a lot with abdominal exercises and other body weight moves too.

I also get discomfort around my knees during certain leg exercises, I'm not sure if it is caused by weak muscles that are connected to the knee but how could I figure this out?

Ideas on how I can increase my endurance overall? It makes power days a real pain since I can't seem to increase my max lifts and have been stuck at the same weight for a while, despite trying to increase.

Some background info: Ectomorph, veering on the meso side, body comp. I eat a lot throughout the day but try to limit carbs to before and after a workout, and I am never short on energy. I take BCAAs, arginine, glutamine and a small amount of creatine before and after a work out. I warm up before lifting but save the actual cardio/HIIT to after a workout. When I say hypertrophy days I am usually using 65% of a 5 rep max and trying to hit threshold by rep 12, or pyramiding down.

Also, my gym (planet fitness), does not have free weight barbells, and my range of motion is too large to feel any sort of stretch when performing deadlifts, what can I do to compensate? These are a clutch move for me.

Hey Dodge, this is something I can relate to all too well. Hang in there. It will take time to build up your endurance, but it can be done, of course .

Seems like one of the bigger problems is that you mentioned you have been "off and on". This is probably holding you back a bit in terms of endurance. Consistency builds endurance just like anything else. You can't run 10K every month and expect to get any quicker. First I would try to be a little more consistent. Your body will adapt. My work outs from 5-10 years ago look nothing like they do today. 9 sets for back and 6 sets for biceps for ONE workout was all I did when I was starting out, not there is much more volume.

As well, I have never done the workout by Layne which you mentioned, but from what I remember, isn't his program fairly volume? It would seem like even the most dedicated gym goers would have trouble hitting it hard or maxing on lifts through out each workout. Maybe which to a program that has a little less volume. Less volume, more intensity. The HIIT is probably burning you out a lot as well. Especially after workouts.

Lastly, how is your diet and sleep schedule? If you are not eating enough or getting enough sleep each night, this could hurt endurance as well.

I'm sure you have most of these covered, just food for though.