Connection issue Comcast home to ComCast Biz

I am having a continuous connection issue between my employees that are local Comcast home customers and the office that has Comcast Biz. Other employees with other ISP can access and Comcast 800 help, can access from their location. The software company (they access from Toronto with no issue) that I am working with was trying to work with Comcast to find the issue. Comcast said they don't see an issue as they can connect. the final recommendation from the software company was to maybe try a different isp provider for the office and drop Comcast as it is only comcast to comcast. I do not have a designated IP. Use an IP addres to connect from home offices through a browser. Any Sugestions.