Q: My husband and I both have iPhone 5s models. While the batteries don't hold a charge very well, the phones still work. But I've heard a rumor that iPhone 5s models won't work after Dec. 31. Is that true?

Julie Oberle, Eagle, Idaho

A: No, that's not true. Old iPhones will continue to work until they are worn out or their batteries no longer hold a charge.

But this brings up an interesting question. Are your phones obsolete? The iPhone 5s is obsolete in the sense that it hasn't been sold in the U.S. since 2016. But it is still current in that it can use Apple's most recent operating system, iOS 12.4, that was just released.

There have been unsubstantiated rumors that the iPhone 5s won't be able to use the next Apple operating system, iOS 13, but that is far from certain.

And even if the 5s is stuck using an old, unsupported operating system, you can continue to use it without concern. The only drawback is that the App Store will begin to have fewer apps that can run on your phones.

To avoid being flooded with e-mails from frustrated Windows 7 users, I have to explain why it is safe to continue using an outdated iPhone operating system but not the outdated Windows 7 PC operating system, even though both will no longer get security updates.

When this happens to Windows 7 in January 2020, the operating system will be vulnerable to virtually every new piece of malware on the internet. That's because of the way Windows is designed (not as well as it should have been) and because Windows 7 is such a big target for malware writers (35% of all PC owners still use it.)

The iPhone operating system is better designed from a security standpoint, and the iPhone 5s in particular represents a tiny target for malware writers, just 1.3% of all smartphones in use. (In addition, the iOS 12 operating system your phones use won't be on many iPhones once iOS 13 is available — making your phones an even smaller target for malware writers.)

Bottom line: Almost nobody writes malware for the iPhone, so you can keep using your iPhone 5s models indefinitely.

Q: I tried to reset my TP-Link router by typing its IP (Internet Protocol) address into my Google Chrome browser. I got the message: "You have no authority to access this router." I was able to log into the router using the Opera browser. Unfortunately, I allowed an online help service to have remote access to my computer, and I'm concerned that they may have put malware on my PC. But scans with MRT, Windows Defender and Malwarebytes found nothing. What can I do?

Craig Turns, Weatherford, Texas

A: I think your PC is OK. The "no authority" message probably did come from your router as a result of a software incompatibility between TP-Link routers and some web browsers. If you can access the router with the Opera browser, that is probably the best solution. You should never allow a stranger online to have access to your PC. But you did the right thing by running security scans. (I am assuming that "MRT" is really MSRT, or Malicious Software Removal Tool. If not, download MSRT from Microsoft at tinyurl.com/z85al7o).

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