Your experience with free WiFi / alternatives in Japanese apartments

Hi everyone, this is my first post here so I'm hoping some of you can help.

I'll be moving to Tokyo in January for 6 months, and intending to rent a studio apartment. Ideally I would like to source my own internet provider so I have more control, but most apartments I'm looking at offer preinstalled WiFi available in "all rooms."

I'm wondering about people's experiences with this free WiFi as after researching extensevily, I can't find what providers or plans these companies/ landlords go for. Is it generally safe to assume it will be terrible? I have researched the Docomo and Rakuten 5G plug-in router, and they seem like viable options, but would love to hear your experiences with them. Is it possible to request a plan upgrade? Any other alternatives you have tried?

I will need pretty good WIFI while I'm in Japan as I'm self-employed and will be working from home 3 days a week. My work requires me to be able to join online meetings effectively so this has been on my mind a lot, so I'm turning to reddit! Thanks everyone!

by carr0t_juice