HP Microserver not connecting to new router AC1900

> I have a HP microserver.

   Does it have a model number?  Is it running some operating system?

> I have recently bought a AC1900 [...]

   "AC1900" is a speed, not a model number.  Ever helpful, Netgear
product packaging emphasizes speeds like "ACxxxx", but that's not the
model identifier.  Look at the product label.

>  Model: R7000|Nighthawk AC1900 Dual Band WiFi Router

   Is that accurate?  Firmware version?

> [...] but I cannot access my microserver.

   Whan you do what, exactly?  "cannot" is not a useful problem
description.  It does not say what you did.  It does not say what
happened when you did it.  As usual, showing actual actions with their
actual results (error messages, LED indicators, ...) can be more helpful
than vague descriptions or interpretations.  "access" is no better.

> [...] How can I connect my microserver to my computer through my
> router?

   Ethernet cables?  What, exactly, does "connect" mean to you?  What,
exactly, would you like to do?