A lot of buffering over the internet streaming from my pc on Infuse. My pc is a updated rig

I am streaming 1080p from my pc at home to my iPhone out and about. Video plays at first for a few seconds but then buffers. I tried multiple locations.

Oh yeah my connection is 1 Gbps fiber connection both speeds same.

Can you run netperf on your computer (netperf -s) and then run it from an iOS app (I use he.net network tools). This will give you the real world transfer rate from your iPhone to your PC.

Additionally how are you streaming? SMB, WebDAV, plex? Are you using a VPN? Does your router have any packet inspection or security features that might interfere with traffic (asus ai protection program another IDP/IPS)?

You can check with a speediest from your Pc.
1 Gb upload is nearly impossible for a normal home connection.
However even a 100 mb is plenty to stream 4K so 1080p is a breeze.
Your problems most likely lie elsewhere. It could be your mobile provide, some limit speed at busy times even if your phone says LTE. And I hope you don’t use hotel WiFi: those are the worst.
In my experience (I travel a lot) Plex is the best protocol for streaming over a mobile connection.
Infuse in the past was not optimal but latest versions are much better in buffering and ensuring a smooth playback