A quarter of people say their broadband service has deteriorated since the start of the pandemic.
A survey by ComReg has also found that 60% found no change in their service, despite more people working remotely.
Meanwhile, one in 5 people in the 25-34 age bracket found their mobile data has deteriorated since last March.
Former Communications Minister Denis Naughten says mobile networks have faced issues in recent months due to demand.
"FDuring the restrictions last November there was quite frequent interruptions in relation to all of the mobile broadband services.
"There is a need to look at our mobile network across the country and see how we can augment and support that to deal with the problems that are being experienced."
