You can ask the other companies for "feedback" even though they might not be truthful at least you asked. Sometimes the other person(s) is just better suited to the role.
But this stood out for me in your OP "I struggle to connect on a personal level, break the ice and make the other person feel at ease."
Many Engineers are a bit introverted and some are downright borderline Autistic, but you need to go in armed a bit better.
So basically like a first Date, first impressions count. Many studies have shown that interviewers, who are often not properly trained or coached, make their mind up in the first 30 seconds. So get there early or on time to cool down and get composed, look smart, avoid "jokes" or humour, LOOK PEOPLE IN THE EYE, and right at the start when you've introduced themselves or shaken hands if that looks like it is appropriate, have a rehearsed line or two so something like "Thank you very much for seeing me today and I hope this isn't the last time we meet, or and I hope I can demonstrate that I'm the right person you're looking for. Then smile. Act confident, but not too "smart". Don't fidget, sit up straight have your arms in a neutral position on your thighs or lightly crossed low down and sit back in the chair, but not rigid with fear. Listen to the questions and have a few prepared answers to common questions. If there is a handshake make sure your hand isn't sweaty, grip firmly, but not a death squeeze and one shake is enough. Personally I hate "hand crushers" and equally a "wet fish" handshake is unappealing. Practice if you need to and bring a tissue with you to wipe your hands (and brow if necessary) just before you go in or go to the bathroom beforehand. Interviews are know to be a very poor way to pick good people, but companies love them as it lets them see the person behind the paper qualifications and experience.
The better interviewers will see you're a bit nervous, as you should be, and start with some simple small talk like questions such as "Did you get here alright?" They don't want a simple answer like "Yes" or "No problem", but equally don't want a 2 minute step by step recount of how you got there. So again prepare a bit and say something like "It was relatively straightforward, it took a while to get through [some interchange somewhere], but only took me about 30 / 40 minutes [or whatever] so commuting will be straightforward." Even if its not, don't make it seem like it will be a huge slog every day to get into the office.... or even something like "Did you have a good weekend?" Again have something prepared to show you're not a stay at home recluse who has no friends or family, so maybe something like "Yes, I met a few friends on Sat and we went for someones birthday / had a BBQ, then Sunday I played football or took my son for a bike ride or a run or something. Just not " not really, just watched TV and played Minecraft until 2am". Think FIRST DATE here. Think your best weekend in the last year and assume that happened this weekend even if it didn't. Showing passion for anything is often seen as a good thing, so long as it's not obsessive. But don't lie or make something up as you then discover that the interviewer is even more passionate abut whatever it is than you are.....
For the actual interview do the same.
So e.g. if someone asks why do want to leave your current job, say something like "I've been there now xx years or months and whilst the company is good and the people are good to work with (NEVER slag off your company or fellow workers even if the place is a hole and they are people you would cross the street to avoid meeting), but I feel I'm not growing or gaining experience and feel that the job / post you have available will allow me to make use of that experience, but in a different way or field.
So try and think beforehand how to make something you've done applicable to the role you're looking for.
Listen to the question and if you don't understand or are unclear about slang or abbreviations then ask. Just say something like, I'm sorry but I'm not familiar with "XYTRDD" in my current role or company, can you explain what that is please? Better to do this than spend 2 minutes waffling about something where it becomes clear you haven't understood the question. Also don't be afraid to say, I'm sorry but that is an area where I haven't been involved, but would like to know more about. Not everyone will tick every box, so don't worry too much about that.
It's been a long time now since I was in that position, but sooner or later the stars will align and you'll get the job. But recognise your faults and failings and try doing something about it. Good luck.