Slow input into shell over wifi on Ubuntu 18.04

I am running an ASUS Chromebox2 with Ubuntu server 18.04. The Chromebox2 is connected to the wifi router right next to it over 2.4Ghz and my host is in the same network, also right next to the wifi router.

When typing into the shell over SSH I can see the characters appearing with a slight delay. When I plug the Chromebox into the ethernet port of the router, it's fast. However, in the longterm the Chromebox should be connected via wifi. How can I troubleshoot that problem?

My network related hardware details:

$ sudo lshw -class 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: enp1s0
       version: 0c
       serial: a8:1e:84:da:92:7a
       size: 1Gbit/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 firmware=rtl8168g-2_0.0.1 02/06/13 ip=192.168.1.135 latency=0 link=yes multicast=yes port=MII speed=1Gbit/s
       resources: irq:18 ioport:2000(size=256) memory:e1100000-e1100fff memory:e1000000-e1003fff
  *-network DISABLED
       description: Wireless interface
       product: Wireless 7260
       vendor: Intel Corporation
       physical id: 0
       bus info: pci@0000:02:00.0
       logical name: wlp2s0
       version: bb
       serial: 34:f6:4b:73:41:6e
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
       configuration: broadcast=yes driver=iwlwifi driverversion=4.15.0-58-generic firmware=17.948900127.0 ip=192.168.1.180 latency=0 link=no multicast=yes wireless=IEEE 802.11
       resources: irq:52 memory:e1200000-e1201fff