It is not prohibited to play at PokerStars from another IP address and everybody can connect to poker room from any device both from mobile phone and personal computer. However, the rules of PokerStars license agreement prohibit the player to intentionally conceal his IP address with the help of additional programs as it is described in details later in the text.
Each personal computer has its own IP address. This address can be both the static (it is constant as it was created manually) and dynamic (every time address is updated during the device reboot). Depending on your provider your computer can have either static or dynamic IP address.
Let's assume that you constantly played at PokerStars from your “computer A”, but after a while, you decided to buy a new “device B”. The new computer will have another IP address and during the first connection to a poker room from “device B” the support service will send you immediately the following e-mail:
Dear Player 1,
03/01/2018 Your account (Payer 1) was used for entry from another new device.
IP address: 126.96.36.199
Location: UA 30
If it is your new device in this case it is not required from you any additional actions. If you didn’t enter with your account from a new device, you should answer this letter.
PokerStars Support Service
It follows that PokerStars doesn’t prohibit playing from different IP if it is done not with the aim of fraud.
But if the player will make frauds and try to change IP address independently with the aim of concealing his location etc., he may be subjected to sanctions from the poker room.
Information from PokerStars’ official site
It is prohibited to use VPN/ proxy servers/ random IP address generators because they can give false information about Your location or place of residence.
Attempt to bypass the ban may threaten with a closure of the player’s account with confiscation of funds.