Have to use IP when UNC while on VPN

I set up a VPN from my home to my small business office and all works fine EXCEPT:

When I UNC to a PC on the work network I have to use IP instead of name. What am I missing? Not a huge deal at all but I wouldn't mind fixing it.

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EXAMPLE:

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I want to \\mypc\d$

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But I have to \\192.168.13.144\d$