I think it would be easier to change the IP range of your home network than to try and change your office network. The two networks (office and home) need to have different network address ranges otherwise, as Bob indicates above, routing of network packets get confused (this refers to the routing software on your computer as well as your network routers).
Most home routers come configured to use a 192.168.x.x address range; typically, they are automatically configured for the 192.168.1.x range. The easiest thing to change is your home network so it uses a different 192.168.x.x range of addresses than your office network. For example, the 192.168.2.x range of addresses.
How you make this change in your home router depends on the brand and model of your router. On most routers, you can login directly to the router's admin page by pointing your browser to the x.x.x.1 address (in your case, try typing
into your browser's URL or address bar) when you are at home and are not using the VPN (turn the VPN off). You will probably have to provide a userid and/or password. If you don't know the userid and password you can search the web for the default values (include your router brand and model number in the search). If the defaults don't work and you can't remember what they were changed to you'll have to hard reset the router to get the defaults back (again, search the web for instructions specific to your router).
Once you have successfully logged into the router's admin pages, there will likely be a setup or basic setup page (probably the first page you see) or a LAN setup page. What you are looking for is a place where you can specify the local network IP address. In your case, you should find this field filled in with 192.168.1.1 and there will probably also be an IP subnet mask field next to this, with a value of 255.255.255.0. Change the IP address to something like 192.168.2.1 or 192.168.3.1, etc. Anything that is different than the IP address range that is used at work. Leave the subnet mask set to 255.255.255.0.
After you've made this change you should reboot your router (or power it down, wait one minute and then power it up), and you should also reboot any machines that are connected to your home network after you've reset the router. Your machines need to get assigned new IP addresses in the new address range that you setup in your home router or they will get confused and won't work on the network.
If any devices on your network have statically assigned IP addresses you will have to change those manually. If you do not know if you have a device with a statically assigned address it means you probably do not have any devices with statically assigned addresses.
Hope that makes things work better!