Hi NeoChen176
Do you want to do this as part of an upgrade path for your environment?
Here is the Horizon Upgrade overview KB
Horizon 7 Upgrade Overview
Depending on your needs you could install one more 7.1 connection server then upgrade it to 7.5.2 so that it is still part of your Pod. Then after testing make a plan of action to upgrade the remaining servers to match.
VMware does not recommend staying on different builds of Horizon for long but it supported as part of an upgrade path.
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Joe Graziano
Senior Solution Engineer - EUC Federal
VCP7-DTM, VCP6-DM, VCP6-DCV
vExpert, vExpertPro
jgraziano@vmware.com