Same here !
If i have some time, I string them along and keep them on hold while the computer is "booting up". Tell them it has really gone slow so there must be a virus. You can make a cuppa whilst keeping them on hold.
The theres the postman at the door, the dog needs to go out, the cat needs feeding, all the while the PC is booting up.
Finally, after booting up, listen to the instructions they give & pretend its taking too long (but do nothing actually on the pc).
And then say despite following the instructions,. nothing is happening ! Let them scratch their head in trying to troubleshoot more.
Finally, ask them which router model number they are after and then quote them a different router model to the one they talk about.
Final nail in the coffin is tell them you are using Linux or Apple! This really annoys them and you can have a chuckle and a laugh.