Ipad/iPhone charge port

Hi, I have been having trouble charging my iPad 6 gen refurbished. I have had it for a little more than a year and I use an otter box defender. I was wondering if it could be damaged or just filled with dust and debris. It works with some chargers, but lower power chargers don’t work. I also have to plug it in 2 or 3 times to get it to charge, but it will charge to 100% fine. Thank you!