Father and son as tenants- son fights with father once in a while

[Mark Berge]

Hi All, these are normally model tenants, they are on their 2nd year lease and take care of the house and pay rent on time. Problem is that the son works from home and the father is retired and is also at home every day. I was over their today doing some small repairs and the father did something to the router and the son started yelling at him to not touch the router. Other times I have been over there and the same kind of thing happens. This is my first rental property and their lease is up for renewal in July. Not sure if I want to renew their lease. I have heard sometimes husband and wives can also fight. Hard part is when if you self manage like I do and you are over there when they fight, not good. Any feedback? When the last renewal was up, I had to push the son to either sign the renewal lease or give his 30 days to move out. The son is divorced and I kind of know why, he is sometimes a hothead.