Not enough info.
Some thoughts though:
Set wireless channel manually, do not use AUTO. Choose a different channel than the one you are using now.
Problem is as likely to be on the workstation NIC as the router, so do full diagnostic on your NIC and NIC drivers also.
Encryption problems....diagnose and trial wthout encryption then with altrnate encryption scheme.
Other wireless phones, transmitters near router or workstation.
Wireless strength set too high when close or too weak when distant.
Many other possible causes but without info on NIC and your network layout too vague to discuss.