Wifi or Ethernet?
I can't think of a reason you would need to upgrade it.
It has a slot for a tiny M.2 card, so you could put a faster WiFi adapter there. It also has a single 1x PCIe expansion slot, so you could get a low-profile expansion card as well. Also USB Wifi and even ethernet adapters you can buy.
Really it is a very, very low end computer. You would be better off investing in a new system.
I retired my AMD e350 based HTPC several years ago when it became less capable of common web browsing tasks. And it was fully loaded with a graphics card, 8GB of memory and I even overclocked the CPU a little. Added a CPU fan (it was a passive cooled system)