My Wireless router experience is a bit limited. I have one and have set it up. However, the signal wasn't good and I ran a lead from a port on the router to the distant computer. Then disabled the wireless capability of the router. The aerial is in a drawer somewhere now. If your computer(s) are always used in the same place, this might be an option. No wireless security considerations are necessary this way either.
Things that I've read about causing wireless connection problems (other than a weak signal) are interference from other wireless equipment that is either in the house or nearby. Anything like that where you are?
I came across
this article regarding signal dropping that you might like to read. Perhaps you could look into the advice given. Maybe others here who are using a wireless set-up will be able to advise further.