Infertility/tips

When is the best time to have intercourse? I have done it every other day during my ovulation cycle and still not pregnant. I've also tried every day as well. And I've had 6 <a href="https://glowing.com/glow-fertility-program">IUI</a> with no success. :( my husband and I have been trying for 5 years. I had one miscarriage 2 years ago and we have been trying ever since. We see a fertility specialist, had everything checked and all our blood levels and sperm levels are where they are suppose to be. They said we have "unexplained infertility".  Any tips??