kernel = 2min boot with SSD

Question

I'm an intern and try to find out why our system is booting slowly. My Ubuntu/Linux knowledge is limited (6 months of private experience with WSL).

Workstation, SSD, no dual boot, Ubuntu 16.04 Xenial.

systemd-analyze
Startup finished in 1min 53.217s (kernel) + 8.170s (userspace) = 2min 1.388s

Blame option showed NetworkManager-wait-online.service with 7.099s (all other services in ms range) and this forum suggested I simply disable the service. I don't know if I should, I don't wanna mess things up. Also I'm not sure if it's a network boot. How can I check this?

~$ free -h
              total        used        free      shared  buff/cache   available
Mem:           7.7G        823M        5.4G        169M        1.5G        6.4G
Swap:          7.9G          0B        7.9G

~$ sudo lshw -C network
  *-network               
       description: Ethernet interface
       product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
       vendor: Realtek Semiconductor Co., Ltd.
       physical id: 0
       bus info: pci@0000:01:00.0
       logical name: eth0
       version: 0e
       serial: b8:ae:ed:ff:93:2f
       size: 100Mbit/s
       capacity: 1Gbit/s
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full ip=129.132.113.166 latency=0 link=yes multicast=yes port=MII speed=100Mbit/s
       resources: irq:128 ioport:ec00(size=256) memory:df218000-df218fff memory:df210000-df213fff
  *-network DISABLED
       description: Wireless interface
       product: Wireless 7265
       vendor: Intel Corporation
       physical id: 0
       bus info: pci@0000:02:00.0
       logical name: wlan0
       version: 59
       serial: 48:45:20:af:4e:75
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
       configuration: broadcast=yes driver=iwlwifi driverversion=4.4.0-43-generic firmware=17.352738.0 latency=0 link=no multicast=yes wireless=IEEE 802.11abgn
       resources: irq:131 memory:df100000-df101fff
  *-network
       description: Ethernet interface
       product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
       vendor: Realtek Semiconductor Co., Ltd.
       physical id: 0
       bus info: pci@0000:03:00.0
       logical name: eth1
       version: 06
       serial: f4:f2:6d:06:6d:1b
       size: 10Mbit/s
       capacity: 1Gbit/s
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=half firmware=rtl_nic/rtl8168e-2.fw latency=0 link=no multicast=yes port=MII speed=10Mbit/s
       resources: irq:129 ioport:d000(size=256) memory:df000000-df000fff memory:d0000000-d0003fff

~$ cat /etc/network/interfaces
# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback

~$ lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 238.5G  0 disk 
├─sda1   8:1    0   512M  0 part 
├─sda2   8:2    0     1M  0 part 
├─sda3   8:3    0   7.9G  0 part [SWAP]
└─sda4   8:4    0 230.1G  0 part /
sr0     11:0    1  1024M  0 rom