xSIID NFC + LED cannot write

Hey there,
I am having a problem with the NFC chip I installed 1,5 weeks ago. I have been able to read without problems for 2 days now. But whenever I try to write it tells me that the NFC tag is not supported. Any idea what I can do?
Thanks
Nad

What phone and app are you using?

I have an iPhone XS. And have first been trying with NFC Tools and then with NFC21 tools. Same result.

Is it the xNT or NeXT? Do you have a Proxmark?

Are you comfortable posting a full scan from How to share NFC chip data via TagInfo app - DT Info - Dangerous Things Forum

https://developer.apple.com/forums/thread/702048?page=2

What are you trying to put on the tag? Some people are saying apple is dumb and will not let it work at all if you try and do thing like WiFi information.

It is this one xSIID NFC + LED Implant - RFID & NFC Chip Implants and Biohacking products (dangerousthings.com). And no - no proxmark.

I basically only tried to connect to a website for the beginning. Sth my phone was able to do with a standard ‘stick to the wall’ RFID tag. So should work with this one as well. But true, an iPhone tends to be a bit fickle now and then… Maybe I should check with some friends’ phones this weekend that are not on the apple cosmos.

I tried reading it - but it only gave me this info while it said that the tag could not be properly read