Apparently the WiFi doesn't work properly when you use the microwave
「電子レンジ使用時に無線LANの通信環境が悪くなるようだ」は英語で Apparently the WiFi doesn't work properly when you use the microwave もしくは The WiFi doesn't work properly when the microwave is being used になります。
電子レンジ - Microwave
使用時に - when using / when you're using
無線LANの通信環境 - WiFi, wireless intranet
悪くなる - gets bad (doesn't work properly)
よう だ - Apparently, I heard that
無線LAN - Wireless Local Area Network (WiFi)