No Man's Land: Bk.5: Gateways by Christie Golden
Left behind by a long-vanished civilisation, the mysterious portals known as the Gateways can enable spacefarers to travel unimaginable distances. Their discovery opens the door to a whole new era of exploration...and who knows what may be on the other side? Throughout the Galaxy, an ancient network of interstellar portals has been reactivated, instantly linking distant planets and civilizations. Back home in the Alpha Quadrant, Starfleet can devote all its considerable resources to coping with the Gateways crisis, but in the Delta Quadrant, there is only the Starship Voyager...Just as Voyager enters an unusually hazardous region of space, the ship and its crew are confronted with a flood of lost and disorientated starships from all over the galaxy. Accidentally transported incredible distances by the unpredictable Gateways, the diverse alien castaways regard each other and Voyager with hostility and suspicion. Captain Janeway suddenly finds herself struggling to hold together an extremely fractious fleet of dislocated alien vessels even as the newly awakened Gateways hold open the prospect of finally bringing her own ship home!