In oral or informal situations, we usually say “网卡了”, it means "the internet is stuck".

网速很慢/网络不稳定/网络容易中断

网络不是很好

Hi Nicole, For "there could be interruption during the chat" you could say: 聊天可能会中断。 For the ways to describe the internet connection issues: 网速慢 - Literally means the net speed is slow. 网络不好/差 - The connection is not good/bad. 信号不好/差 - The signal is not good/bad. 网络信号不好/差/不稳定 - The network signal is not good/bad/unstable. 你的声音断断续续的 - Your voice is cutting out.