Below are various commands that may help in connecting to various lab instances, some have compression flags to help speed up connections:
NOTE: Can also be used with proxychains

xfreerdp /cert:ignore /compression /auto-reconnect /u:USERNAME /p:PASSWORD /v:IP_ADDRESS

sudo rdesktop -u USERNAME -p PASSWORD -g 90% -r disk:local="/home/kali/Desktop/" IP-ADDRESS

rdesktop -u USERNAME -p PASSWORD -a 16 -P -z -b -g 1280x860 IP_ADDRESS

xfreerdp /u:USERNAME /p:PASSWORD /cert:ignore /v:IP_ADDRESS /w:2600 /h:1400

xfreerdp +nego +sec-rdp +sec-tls +sec-nla /d: /u: /p: /v:IP_ADDRESS /u:USERNAME /p:PASSWORD /size:1180x708

rdesktop -z -P -x m -u USERNAME -p PASSWORD

xfreerdp /u:USERNAME /p:'PASSWORD' /v:IP_ADDRESS

xfreerdp /cert:ignore /bpp:8 /compression -themes -wallpaper /auto-reconnect /h:1000 /w:1400 /u:USERNAME /p:'PASSWORD' /v:IP_ADDRESS

xfreerdp /cert:ignore /compression /auto-reconnect /d:DOMAIN_NAME /u:USERNAME /p:PASSWORD /v:IP_ADDRESS