This Ethernet cable can be a source of RF radiation and so needs to be shielded. There are lots of different qualities of cable category 5, 6, 7 etc. I recommend buying at least Cat 6a SSTP (screened shielded twisted pair) Ethernet cable. Maybe the cable that came with your modem/router is Cat 6a SSTP. In that case you’re OK. If in doubt change it.
And, it’s not just sperm. The results of an animal study suggest that some wireless frequencies may prevent egg implantation. During the study, mice exposed 2 hours a day for 45 days had significantly increased oxidative stress levels. The cellular damage and impact on DNA structure from exposure suggest a strong possibility of abnormal pregnancy or failure of the egg to implant. [12]
In response, we would state that all wireless frequencies currently used by the public are categorized as radiofrequency radiation. People have not been using Wi-Fi for as long as they have been using cell phones, so the research that has looked at long term use of cell phones is very important in considering the long term health risks from wireless and Wi-Fi specifically.

Cell phone safety is a top priority for people all over the world—especially those with children. There are many tips for ensuring that both you and your kids are using your cell phone or smartphone safely—from being careful when you cross the road, to learning the driving laws in your area, which way to carry your phone for radiation reduction, and monitoring and limiting the amount of time your child or teen spends using their device.
The most compelling evidence though comes from a Swedish team of cancer experts whose research stretches back 15 years. The results clearly demonstrate “a consistent association between long-term use of cell phone and cordless phones and glioma and acoustic neuroma”. Overall, they found that using a cell phone for more than a decade significantly increases the risk of a malignant tumour by almost two times with an analogue cell phone and by nearly four times with a digital phone. Interestingly, the risks were even higher for people who had started using mobiles as teenagers.