Ireland RTE2 is the channel I check first whenever a big match is on. Run by the national broadcaster RTE, it launched in 1978 as the country's second TV channel and has carried live sport ever since, from Champions League nights to Six Nations rugby and GAA championship games (https://en.wikipedia.org/wiki/RT%C3%A82).
The simplest legal way to watch is the RTE Player, which streams RTE2 live and free inside Ireland and keeps full replays and highlights for about a month afterwards. Full schedules and catch-up links live on the official site at https://www.rte.ie, which I use to plan my weekend viewing.
One thing I learned the hard way: live streams freeze at the worst moments when the connection is weak. Before a big game I run through a checklist of IPTV buffering tips for sports so the picture stays smooth through extra time.
My routine now is simple. I check the RTE schedule on Friday, test my stream speed on Saturday, and keep RTE2 as the anchor of match night. Between the free live feed, the highlights archive, and a tuned connection, I rarely miss a goal.