We are not able to open some https site from our branch office. The branches are connected with head office.
Branch Offices 10.10.5.0, 10.10.13.0 and so on.
The network between HO and branch offices are done by ISP through DSL Data Line and 4G Wifi. Before few days DSL data lines are being upgraded to 4G. After changing the connection none of the branches which are upgraded able to open some of https site. We noticed this to the ISP but they found that they can able to telnet from new 4G data router to https hotmail.com and many other sites. We have given full access in the firewall (10.10.1.35) to the pcs behind those network (10.10.13.60, 10.10.5.72, etc). No changes have been done on firewall since the up gradation. We have multiple ISP for internet also and tried to route traffice to both the ISP as well but with no luck. For backup every branch is connected with two ISP data. If we switch the problematic pc to other isp data line the problem solves. What could be the problem. Please advice.