You should either have 2 or 3 valves behind the water heater they need to be set to bypass the water heater. Search the site some pictures are available.
As far as the water filter are you sure that you have one?
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Not every R/V, nor water heater and plumbing, is the same. One size does not fit all. One has to know what water heater you have and how it is plumbed to properly identify the steps needed to bypass. Pictures are also helpful.
Same with the water filter. Locations are different across models and even some like units. The factory can/will do things differently as they come down the assembly line.