On a wired connection most of what I said also remains true - router firmware, PC network drivers, hardware failures (network cards, routers, modems, cables), network traffic surges, other software on the PC(sometimes even malware), etc.
To run a tracert follow the guidance in here https://us.battle.net/support/en/article/performing-a-traceroute
You can expect the last few hops to "time out" because they are hidden for security reasons.
As a general rule, it does not hurt to update the drivers on your PC which you can do by visiting the PC manufacturer's website or the maker of the hardware. Try to include video, sound, and network cards at a minimum.
Your router can be a source of problems so ensure the firmware on it is up to date by visiting your manufacturer's website and following directions there. I had to update mine to solve this issue myself.
There are some router software settings that can be tweaked and may help (I will leave that to other players or blues as I am not an expert in those).
Sometimes dealing with your ISP directly is required if you have a failing modem. (often a last resort)
You can try running the game without background applications https://us.battle.net/support/en/article/shutting-down-background-applications
You can run a Malware and Virus scan to rule those out - Download, instal, and update Malwarebytes. Run a FULL (not quick) scan with the game up and gibberish in the login fields. There is some malware that only activates under those conditions. When that scan is done, run a FULL Virus scan using something decent. Microsoft Security Essentials is free and not bad these days.
Those are just a few things you can try and should get you going on the troubleshooting!