Hi, the number of pairs shouldn't affect. Note that there is delay between pairs, so, if you add 3 pairs and you set delay to 10, the bot will process 1 pair every 10 seconds, same way as it would do if you add 200 pairs.
Summarizing, the important thing is the delay. Depending on your Internet connection, you can set it very low, or maybe you need to set it to a high value.
Anyway, you shouldn't have any problem setting delay to 30. A lot of people is running the bot on Binance with 10, even lower. On the other hand, supposing your api key was banned, Binance would ban your access to the api, that is, it has nothing to do with Binance website. Do you see any error message in bot logs?
My guess:
1- It was just a coincidence. Binance website was down at that momment.
2- Your connection was dropped at the momment you tried to load Binance website. Maybe it was a connection drop? Did you try to load other websites after trying to load Binance website?