Q: Over the last three years, I've been the victim of harassment via the internet and cellphone calls. I've reported it to the police and the FBI, but they haven't been able to stop it. Do you have any idea what I can do about the following:
– My husband and I use Wi-Fi to access the internet on our iPhones, but I'm having trouble logging in to social media, particularly Facebook. The activity logs in both our Facebook accounts show that IP addresses other than ours have been logging in to the accounts.
– About two years ago, my Gmail account suddenly started getting about 400 pornographic spam e-mails a month.
– My iPhone has failed to receive multiple phone calls, e-mails and texts that friends and relatives say they sent to me.
– On my previous phone, an Android, calls from the local sheriff's office were cut off before I could answer them. A deputy said my phone number appeared to be blocking him (it wasn't.)
– When the same Android phone was sitting on a dresser, my husband I heard it make odd noises in the middle of the night.
– My tablet computer started getting locked out of my Instagram account at the same time that an unidentified white cargo van stopped in our neighbors' driveway. The driver told the neighbor he stopped because he liked their house lights.
Caroline Pennington, Franklin, Ohio
A: The common thread in all these incidents is wireless communications.
One possibility is that someone is blocking your Wi-Fi and cellphone signals using an illegal device called a "jammer." Another possibility is that someone has hacked your home Wi-Fi router and installed malware on it that is affecting all of your devices.
How could your wireless signals be remotely blocked? A jammer near your home can interfere with the Wi-Fi, cellular or GPS radio frequencies. (See the Federal Communications Commission website, tinyurl.com/jv4v24g). Although jammers are illegal in the U.S., they can easily be purchased online.
The only way to prevent jamming is to report it to the police. I suggest you keep a log of when Wi-Fi or cellular signal interruptions occur. Note the date, time and duration of each incident and also take note of any unfamiliar vehicles in your neighborhood at the time (the range of jammers varies, but is often no more than 150 feet.)
How are Wi-Fi routers hacked? Sometimes hackers use sheer technical skill, but more often they gain access because no one changed the router's default password (such passwords are well-known among hackers.) Once a router is hacked, it can spy on your internet communications (stealing social media passwords, for example), help hackers attack your other Wi-Fi network devices and disrupt your internet access.
Replace your router. Many routers have their own protective firewalls (see tinyurl.com/mt6cfml). And, of course, change the new router's default password.
Remember that if your router has been hacked, your computers may have been, too. Download the free Malicious Software Removal Tool from Microsoft (see tinyurl.com/z85al7o), or the free version of the Malwarebytes security program (see tinyurl.com/j32jr94).
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Steve Alexander covers technology for the Minneapolis Star Tribune. Readers may write to him at Tech Q&A, 425 Portland Ave. S., Minneapolis, Minn. 55488-0002; email: firstname.lastname@example.org. Please include a full name, city and phone number.