A Bitaxe connects to a pool with standard Stratum settings, entered in the AxeOS dashboard:

• Stratum URL / host — the pool's address.
• Port — the pool's Stratum port.
• Username — for a solo pool this is normally your own Bitcoin payout address (so a found block pays you); for a shared pool it is your account/worker name.
• Password — usually anything (often x); some pools use it for options.

Neutral, commonly-used options include a solo pool such as solo.ckpool.org (you keep the full block reward if you win, minus the pool's small fee), a public or self-hosted pool (e.g. running your own Public-Pool / Stratum endpoint for full sovereignty), or a conventional shared pool if you prefer steady small payouts over lottery variance. The choice is about variance and sovereignty, not about making a single-chip device profitable.

It is good practice to set a backup pool in AxeOS so the device keeps hashing if the primary is unreachable.