Cannot update Itunes because of network problem

Perhaps this scenario is a backhanded attempt to get your Mac an upgrade

to a later supported macOS such as Mojave 10.14.6. ~ Or maybe a bit too far

with what might be fail leap into Catalina 10.15.7. Given that shows way much

will change; to file structure and whole system security??

After Mojave 10.14.6 (or last step to that upgrade, as last digit may be higher)

the path back, short of using a different Mac; would be well beyond backups.

The link to try and get that version download, is among chatter on this page:

How to download and install macOS - Apple Support

//support.apple.com/en-us/HT211683

[A 'Time Machine' app in your Mac, backs up a dedicated external hard

drive via USB cable; but it has limits, & this runs almost fully automatic.]

An additional backup to have more than one, might be 'full system' Clone

and made on external bootable hard drive using SuperDuper, or CCC.

In itself, is not necessarily future proof; other OS changes are ahead.

Well, the Mac has some issues; but the updates for iOS for iPhone/iPad, has

new version corrections going ahead. To try a voodoo fix (safe boot) for Mac

is an easy enough conjure; so long as Safe mode start up, really happens.

Use safe mode on your Mac - Apple Support

//support.apple.com/en-us/HT201262

Given your Mac has intel-based hardware, instructions to start in Safe mode

are fairly simple; expect this to take time, once actually in Safe mode. The

ways to tell should be explained in the article; or in different support links.

Newer versions iOS are out, but have no idea if that resolves any incompatibility

with these older Mac OS builds. [High Sierra is what my main Late 2012 Mac mini

server runs, on one of its two factory-installed hard drives; it can dual boot, too.]

My iPhone is an older one, that cannot be upgraded; so that's not going further.

(Second iPhone8 would need a second account, & new SIM card; not doing it.)

.Sorry to not have exacting answers; this is a volunteer with more offline than on.

PS: Problems at my end, made this reply later than intended; so our posts crossed.

Apple Stack Exchange was able to find a solution for an iPhone on IOS 16 on High Sierra where iTunes refused to update to allow synch due to a “network problem.” But involved adding Xcode: https://apple.stackexchange.com/questions/461301/mac-os-10-13-6-and-newer-mobile-devices-not-working-with-itunes-12-8-3-1-mobiled

The newest iOS and macOS 'version changes' are listed among these

entries, & go back somewhat, to those not frequented this go-round.

Apple security releases - Apple Support

//support.apple.com/en-us/HT201222

..Obviously some time passed, looking back for earlier build versions..

And not sure about any Xcode cited by third-party sites.

There are those who are on iTunes 12.8.3.1 and on High Sierra and who upgraded their iPhones to IOS 16 were able to get a software update without getting the “network problem.”

My bad. I believe IOS 16 was the last IOS to be supported by Mojave. But wouldn’t it give a different error than a “network problem”?

I am happy it worked for you too. No problems synching with everything (Photos, Calendar, Contacts, etc)? Apple Stack Exchange is pretty good in finding answers. The Xcode had the SDK for IOS 12-17.

How did you eventually update your iTunes? I had the same problem.