forget using ivms 4200 if mobile access is a requirement
i setup up quite a few for clients and still use PCNVR as its so much easier for mobile access and it still supports the latest cameras only downside is the non 265 support but just means computers working a little harder and and with advances i just grab a 2nd hand Dell Optiplex 1030 for like 300$ whack a 4TB purple for $200 and a low profile Nvidia GT 1030 for $150 and run 20-30 5MP-8MP cameras no problem
using ivms 4200 for mobile works but have to redirect and open ports for every single camera