Portal Submissions timing out in Ingress Prime? Try this:
When you take a picture of a portal and it's surrounding area for a submission, the app takes the two photos with your phone's camera app. Depending on what model phone and settings it's on, the picture resolution could be huge.
So before I submit the portal, I reduce the resolution of the pictures I'm submitting.
I usually do this by taking the pictures before hand, and then screenshotting the photos on my phone screen. But you could see if you can change the resolution in the app or phone settings, or reduce the resolution using some other means.
Then when you want to submit the portal, choose your existing lower resolution photos instead of taking a new one in app.
Doing this reduces the time to takes the app to submit the portal and makes it more likely to submit in an area with not too good signal before it times out.