As WeCom is a SaaS software, the server domain names and IP addresses are accessed over the Internet. If the domain names or IP addresses from WeCom servers are blocked by your company’s network security policies, WeCom cannot be used normally. To ensure that WeCom functions properly, you need to allow the domain names and IP addresses provided in the following link.

WeCom server domain names and IP addresses: https://work.weixin.qq.com/h5app/wework_domain_ip/latest