To cut holiday short

Yes people who manage to (usually) keep their dc under control don't necessarily have easy children, if my dc didn't hold my hand I held onto their arm until they grew out of the running off stage. They didn't like it, but I balanced that against them getting hurt.

I’ve been there and it becomes so disheartening. I would say it’s all fairly normal if horribly annoying behaviour. It becomes a cycle of bad behaviour - telling off and no one is having a good time. I would say that humour is your best friend. Laugh, joke, distraction at that age works better than telling off. They stop listening to being told off after a while. So you can save telling off for real bad behaviour. Then the whole vibe is better and happier and things just get easier all by itself.

Stick it out. A lot of the behaviour you’ve mentioned is not that unusual between siblings and it won’t miraculously stop if you go home early.
Out of all the things you mention the constant teasing would be the one I’d find hardest to deal with and worry me the most as there has to be reason for it.
As someone else said above, the arguments over door opening might lessen if you told them that from now on they had to take it in turns. Include yourself in the turns too and if one of them has behaved particularly well gift your turn to them without saying beforehand that this is what you will do. Make a huge thing of how proud you are and you never know it may just make one or both of them realise that good behaviour and doing what you ask brings reward.
As to the stroppiness with the shoes try calling his bluff and let him out without them. Discreetly stick the shoes in your bag and I bet that within a few yards he’ll be wanting to put them on.
If you are not willing to do that it’s probably best that you just accept that for the rest of the holiday you get them both washed and dressed yourself. More work for you but needs must. Anything for a quieter last couple of days.
No matter whether you holiday as a two parent family or on your own looking after the children is hard work. I find that I’m constantly on tenterhooks whenever we eat out or have a coffee anywhere. Even taking them to indoor play is stressful because you need eyes in the back of your head. Make it as easy as you can for yourself - what I’ve learned as a mum of 4 is that being continuously on the go is not necessarily a good thing. Don’t be afraid to tell them that mummy is tired and that if they spend 30 minutes or so quietly in the flat while you have a rest they can have a treat of their choosing afterwards

Go home. I have come to loathe holidays for similar reasons. Much easier to manage children at home. If a holiday for them equals misery for you, it's not a family holiday that's worthwhile. Definitely go home! It might even teach eldest a lesson.

I think you are doing brilliantly. It is hard, really hard. Baby reins are your friend. I just had them in my pocket and would jangle them menacingly and just have them dangling slightly from the pocket - I never had to use them. I think they are both missing Daddy too. My youngest son’s behaviour was always awful when husband was away on business trips. Channel the scariest teacher you had at school. Don’t talk and explain too much - kids just hear blah blah blah. Just say it and really mean it - act being the strict teacher - it does work. Then praise, loads and loads of praise so strict face for one, two word directions - brisk voice, and smiley, lovely face. Children sniff out desperation and hopelessness and it makes them feel insecure and thus behaviours become more extreme or relentless. Teasing is always going to happen, not putting shoes on is always going to happen, faffing is always going to happen but it it all needs to be in balance.

Its not a holiday for you when they are so small. Its the same shit as at home yet just in a different setting 😜

We took DS for a weekend break to the seaside, dh didn’t want to go and was also in a foul mood. O the third day (day before we were due to leave) I got up early packed and said we were going home. Ds was fine dh was rather Shame faced as he knew his role in it. I now invite adult dds and tell dh he can come if he wants. He makes more effort now

It does sound fairly normal for that age. It is exhausting trying. Try rewarding their behaviour when they do the right thing - when they are getting along, putting on their shoes, eating a decent amount of lunch/dinner.
Apparently it's more motivating than quotes of punishment.
Go home now if you are over it!

Maybe my kids are awful (!) but aside from the 6 year old teasing his brother I don't see anything that terrible here. I think it all feels worse because you're on your own with them both (I would never do this, you're brave!) and also you've built up this holiday as something that will be extra wonderful and they're not playing ball. They're probably picking up on and reacting to that tension and pressure. The reason they don't understand why you're angry and furstrated and punishing them is because a lot of this is just them being kids.

You all probably need to relax a bit. I bet you're doing better than you think.

One of the most helpful things someone once told me is that young children have their own timeline and their own agenda. They don't care that it's time to put their shoes on, in their head, they're playing and you're interrupting them. That's their natural state, they can't be made into little robots who obey all instructions at first mention, nor would you want them to. It's about balance. Can't you relax the timetable a bit and go at their pace? That will make things easier. Also, humour is their language so use it. Things like arguing over opening the door are easily solved with humour and lightness (as well as just taking turns!) Pretend you want to do it too, and then spend some time playing a game where you all go in and out of the door, take turns to do it over and over, Why not? If it keeps them amused then great! I think you're just resisting them wanting to be kids some of the time in your OP.

The teasing is different and as lots of PPs have said it'll likely be about sibling rivalry. Your DS6 probably needs tons of love and reassurance, and to feel he still has a special bond with you that's all his own. Could DS4 go to bed a bit earlier than him? Could you make a deal that if he's really nice to his brother all afternoon he can secretly stay up an extra hour with you after the younger one goes to bed and you'll have popcorn and watch a movie together in pyjamas?

Good luck with the holiday!

Well you should not be asking.

You should be telling.

You need to change your parenting.

Consequences if they don’t do as they’re told. The first one being leaving the holiday early.

I have done many solo trips with my DC.
Firstly you need to forget that this is a holiday for you.

This are things that worked for me when DC were little:
Multi Day trips: one day staying on site doing the activityes available next day going off site and doing something else.

On your on site days no pressure to get dressed or out. Just let them be... so 6yo is hungry? Tell him to get dressed so you can go out for food. Ideally you sort out the 4yo first thing so that the pressure is on the 6yo.
Relax & let them guide you- it's ok to miss a puppet show in favour for the playground. If they feel they missed out just tell them there is one in 2 days time...
We've also successfully done days where x chooses the activities for the day (just make sure 4yo chooses first to get his brother to cooperate!)

I find taking them away from the overstimulating kids environment a life saver! No multiple activities on tap just the one thing you have planned. I often use these days to go to the beach or go for a walk in the woods.... different indoor play or even a museum if it's raining... some food or snack shopping.... key is to look for the cheap or free stuff!

I do think you need to adress the teasing separately. Don't give the 6yo attention as I believe some of it is fishing for an reaction from you. Instead focus on the 4yo by maybe giving him a task to do. Once done praise. Next give 6yo a very different task- then praise.

Unpopular opinion.
If 6yo won't get dressed in a reasonable time e.g 20-30 minutes, then dress him. You thought he was a big boy now so it's a bit disappointing. Well done 4yo for doing (thing you're doing for 6yo).
I am saying this to sort the willful delaying and obstructing, but it might help the teasing too. Honestly reading your report of constant teasing which you are aware of but it still continues is really getting to me.
6yo teases 4yo - well at least he can put his own clothes on!
In different ways they are both encouraged to be good at getting dressed.
People have been talking about how the 6yo might feel undervalued, but what about the 4yo? Nobody can/will save him apparently.
I assume you already talk to 6yo about how his teasing hurts his brother's feelings. This will likely raise a more effective opportunity.

You are brave, my girls are this age too but the 4 year old is the wildest.

is there a kids club or baby sitting service you can use to decompress?

Well I agree the consequence should be immediate and not weeks away but she’s said it now.

I imagine this is outside the normal behavior? If this was a vacation issue... I'd absolutely go home early.... they lose the fun because of the behavior and we won't be doing this again until they can show they will behave.... I'd imagine if you tell people why you are leaving early they will understand that their behavior is unacceptable and you hopefully will get them to do better next time... if you brave it again... I think kids can get way overwhelmed on vacation and need to learn the boundaries of acceptable behavior. You are outside of the norm so they are likely testing boundaries with you on your own....Good Luck

Someone laughed (not OP) at posters saying to make sure your 4 year old is always holding your hand and said ‘you can tell you haven’t got wilful children!’ I don’t understand comments like this, no it might not be easy but what’s the alternative? They run off and get lost, hit by a car etc!

This. You need another adult next time.

You can't have a 4 yr old on reins. Max 18mth to 2 yrs surely. 4yr olds should be able to listen to instructions, you bribe them with rewards.

Also, meant to say I think reins are a good idea because obviously of all the stuff you mentioned the running off is dangerous and not on so that needs to stop.

I think it's just small kids being small kids, as they get older I think you forget how much whinging there used to be (usually for nothing).
I don't have much advice but I would just say re the getting dressed, is it the end of the world if you dress them? I know a 6 year old could/should be doing it in theory but if it saves everyone's sanity is it just easier to keep helping for another year or so. They are not going to be 15 and needing you to dress them, they will grow out of it but it seems like you are making a rod for your own back by insisting he does it himself. I'm fairly sure I helped/dressed my kids until they were much older, it helped not having to get changed for PE at school anymore but they could have done it if they needed to.
The teasing obviously has to be addressed but it is very common, I have a 9 and 11 year old and they are still the same so hoping they grow out of it soon!
Anyway good luck op but they really don't sound super badly behaved to me for their age but it's definitely hard work!

Oh OP it's a hard age, esp on your own. I wouldn't go home, try and get through today and try to make it fun and happy ... tricky I know.

I had completely forgotten this as mine are mid 20s now (twins), but I remember packing up and going home early on a caravan holiday (so similar sort of thing), and I had DH with me. They were a similar age and a nightmare so we decided to call it a day. Holidays after that did improve as they got older.

We get around the door/button thing by the grown ups doing the 'fun' tasks like the door/button because it stops the squabbling and there is no competition between the DC. They get given a chance to share the task but any arguing and that days chance is gone, no matter whose turn was last.
Going out is a tricky one, my youngest actively prefers to be home and tries to delay us so the old 'we won't go' trick rarely works (unless it's a very very specific activity). I don't actually have any real advice here, I find myself using desperate measures to get my youngest out the door most days.
BUT making things a race can work! Use a timer to race against, not directly each other and include yourself. Do your shoes against the timer with them, include yourself in the turn taking - I suggest this to model to your older DC how to 'win' without teasing, and stops them directly competing against each other which will cause teasing too.

We use a wrist strap for running off, which does have the desired effect most the time.

And I do try to be the parent that names a child's feelings, I know all behavior is communication and know they don't have impulse control, they don't have developed brains, they can't understand logic until age 6+, but I would tell the older DC they are being mean with the continuous teasing, because it's ruining the day for everyone.
I'd also try and get the bottom of the teasing, but it's so common between siblings that I do wonder if it's just part of being a sibling and having different personalities/needs.

@BloominNora it's really obvious you don't actually know what gentle parenting is.

Well that's unbearable. A lot of it is down to the kid you get too. And their stage. Six can be very difficult.

I haven't read the replies and I think you should probably go home for your own sanity but dc of that that age are bloody annoying so you have my sympathy but, there are two main behaviour issues here, ds4 running off, and ds6 teasing. I would be holding onto ds4 with a vice grip every time we go outside whether he likes it or not, and I would come down very hard on ds6 for the teasing. Take something from him or do a time out or whatever works, I am sorry but constantly explaining to him and crying won't cut it. A certain amount of teasing is normal between siblings, as is whining and refusing to put shoes on etc. I agree with a pp, have a few snacks in and just go with the flow as much as you can.