accessory may not be supported - even on original apple cables

iphone 6s says “accessory may not be supported” when charging.

i have tried multiple original Apple cables as well as 3rd party cables (both mifi certified and not). there are 6 iphones and over 2 dozen good cables around the house (bad cables are clipped and tossed after repeated failures).

i have also tried “reset all settings” and upgraded to IOS 14.2.

i have cleaned out the charger port with a toothbrush, both dry and with a little bit of 99% IPA.

“replace the battery” seems to be a common mantra among problems, but the battery health reads 100%.

any thoughts on now to troubleshoot this further?

i’m not a pro, but i’m not averse to cracking it open and doing DIY phone surgery.

Thanks